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Chemical Principles

Steven S. Zumdahl, Donald J. DeCoste

Chapter 4

Types of Chemical Reactions and Solution Stoichiometry - all with Video Answers

Educators

Chapter Questions

01:55

Problem 1

Assume you have a highly magnified view of a solution of HCl that allows you to "see" the HCl . Draw this magnified view. If you dropped in a piece of magnesium, the magnesium would disappear, and hydrogen gas would be released. Represent this change using symbols for the elements, and write out the balanced equation.

William Mills
William Mills
Numerade Educator
03:47

Problem 2

You have a solution of table salt in water. What happens to the salt concentration (increases, decreases, or stays the same) as the solution boils? Draw pictures to explain your answer.

Ashwani Kumar
Ashwani Kumar
Numerade Educator
08:53

Problem 3

You have a sugar solution (solution A) with concentration $x$. You pour one-third of this solution into a beaker and add an equivalent volume of water (solution B).
a. What is the ratio of sugar in solutions A and B ?
b. Compare the volumes of solutions A and B .
c. What is the ratio of the concentrations of sugar in solutions A and B ?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
00:18

Problem 4

You add an aqueous solution of lead nitrate to an aqueous solution of potassium iodide. Draw highly magnified views of each solution individually and the mixed solution, including any product that forms. Write the balanced equation for the reaction.

Ashwani Kumar
Ashwani Kumar
Numerade Educator
04:39

Problem 5

You need to make 150.0 mL of a 0.10 M NaCl solution. You have solid NaCl and your lab partner has a 2.5 M NaCl solution. Explain how you each make the 0.10 M NaCl solution.

William Mills
William Mills
Numerade Educator
02:10

Problem 6

The exposed electrodes of a light bulb are placed in a solution of $\mathrm{H}_2 \mathrm{SO}_4$ in an electrical circuit such that the light bulb is glowing. You add a dilute salt solution, and the bulb dims. Which of the following could be the salt in the solution?
a. $\mathrm{Ba}\left(\mathrm{NO}_3\right)_2$
c. $\mathrm{K}_2 \mathrm{SO}_4$
b. $\mathrm{NaNO}_3$
d. $\mathrm{Ca}\left(\mathrm{NO}_3\right)_2$
Justify your choices. For those you did not choose, explain why they are incorrect.

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
View

Problem 7

You have two solutions of chemical A. To determine which has the highest concentration of A (molarity), which of the following must you know (there may be more than one answer)?
a. the mass in grams of A in each solution
b. the molar mass of A
c. the volume of water added to each solution
d. the total volume of the solution
Explain.

Iva Lazarova
Iva Lazarova
Numerade Educator
01:14

Problem 8

Which of the following must be known to calculate the molarity of a salt solution (there may be more than one answer)?
a. the mass of salt added
b. the molar mass of the salt
c. the volume of water added
d. the total volume of the solution
Explain.

David Collins
David Collins
Numerade Educator
02:22

Problem 9

Consider separate aqueous solutions of HCl and $\mathrm{H}_2 \mathrm{SO}_4$, each with the same molar concentration. An aqueous solution of NaOH is added to each solution to neutralize the acid. Which acid solution requires the largest volume of NaOH solution to react completely with the acid present? Explain.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:24

Problem 10

Order the following molecules from lowest to highest oxidation state of the nitrogen atom: $\mathrm{HNO}_3, \mathrm{NH}_4 \mathrm{Cl}$, $\mathrm{N}_2 \mathrm{O}, \mathrm{NO}_2, \mathrm{NaNO}_2$.

Lottie Adams
Lottie Adams
Numerade Educator
01:51

Problem 11

Why is it that when something gains electrons, it is said to be reduced? What is being reduced?

Connor Hudson
Connor Hudson
Numerade Educator
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Problem 12

Characterize strong electrolytes versus weak electrolytes versus nonelectrolytes. Give examples of each. How do you experimentally determine whether a soluble substance is a strong electrolyte, weak electrolyte, or nonelectrolyte.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:37

Problem 13

The figures below are molecular-level representations of four aqueous solutions of the same solute. Arrange the solutions from most to least concentrated.
(FIGURE CAN'T COPY)

Marissa Turner
Marissa Turner
Numerade Educator
01:46

Problem 14

Which of the following statements is (are) true? Correct the false statements.
a. A concentrated solution in water will always contain a strong or weak electrolyte.
b. A strong electrolyte will break up into ions when dissolved in water.
c. An acid is a strong electrolyte.
d. All ionic compounds are strong electrolytes in water.

William Mills
William Mills
Numerade Educator
01:44

Problem 15

Differentiate between what happens when the following are dissolved in water.
a. polar solute versus nonpolar solute
b. KF versus $\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6$
c. RbCl versus AgCl
d. $\mathrm{HNO}_3$ versus CO

Anand Jangid
Anand Jangid
Numerade Educator
01:50

Problem 16

Commercial cold packs and hot packs are available for treating athletic injuries. Both types contain a pouch of water and a dry chemical. When the pack is struck, the pouch of water breaks, dissolving the chemical, and the solution becomes either hot or cold. Many hot packs use magnesium sulfate, and many cold packs use ammonium nitrate. Write reaction equations to show how these strong electrolytes break apart in water.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:35

Problem 17

Match each name below with the following microscopic pictures of that compound in aqueous solution.
(FIGURE CAN'T COPY)
a. barium nitrate
c. potassium carbonate
b. sodium chloride
d. magnesium sulfate

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:03

Problem 18

A typical solution used in general chemistry laboratories is 3.0 M HCl . Describe, in detail, the composition of 2.0 L of a $3.0-\mathrm{M} \mathrm{HCl}$ solution. How would 2.0 L of a 3.0- $\mathrm{MHC}_2 \mathrm{H}_3 \mathrm{O}_2$ solution differ from the same quantity of the HCl solution?

Christopher Dzorkpata
Christopher Dzorkpata
Numerade Educator
01:31

Problem 19

A solution was prepared by mixing 50.00 mL of 0.100 M $\mathrm{HNO}_3$ and 100.00 mL of $0.200 \mathrm{M} \mathrm{HNO}_3$. Calculate the molarity of the final solution of nitric acid.

LJ
Lena Jake
Numerade Educator
01:53

Problem 20

A solution of ethanol $\left(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}\right)$ in water is prepared by dissolving 75.0 mL of ethanol (density $=0.79 \mathrm{~g} / \mathrm{cm}^3$ ) in enough water to make 250.0 mL of solution. What is the molarity of the ethanol in this solution?

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
04:48

Problem 21

Describe how you would prepare 2.00 L of each of the following solutions.
a. 0.250 M NaOH from solid NaOH
b. 0.250 M NaOH from 1.00 M NaOH stock solution
c. $0.100 \mathrm{M} \mathrm{K}_2 \mathrm{CrO}_4$ from solid $\mathrm{K}_2 \mathrm{CrO}_4$
d. $0.100 \mathrm{M} \mathrm{K}_2 \mathrm{CrO}_4$ from $1.75 \mathrm{M} \mathrm{K}_2 \mathrm{CrO}_4$ stock solution

William Mills
William Mills
Numerade Educator
13:41

Problem 22

How would you prepare 1.00 L of a 0.50 M solution of each of the following?
a. $\mathrm{H}_2 \mathrm{SO}_4$ from "concentrated" $(18 \mathrm{M})$ sulfuric acid
b. HCl from "concentrated" $(12 \mathrm{M})$ reagent
c. $\mathrm{NiCl}_2$ from the salt $\mathrm{NiCl}_2 \cdot 6 \mathrm{H}_2 \mathrm{O}$
d. $\mathrm{HNO}_3$ from "concentrated" $(16 \mathrm{M})$ reagent
e. Sodium carbonate from the pure solid

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:34

Problem 23

What mass of NaOH is contained in 250.0 mL of a 0.400 M sodium hydroxide solution?

William Mills
William Mills
Numerade Educator
01:56

Problem 24

If $10 . \mathrm{g}$ of $\mathrm{AgNO}_3$ is available, what volume of 0.25 M $\mathrm{AgNO}_3$ solution can be prepared?

LJ
Lena Jake
Numerade Educator
04:39

Problem 25

Which of the following solutions of strong electrolytes contains the largest number of moles of chloride ions: 100.0 mL of $0.30 \mathrm{M} \mathrm{AlCl}_3, 50.0 \mathrm{~mL}$ of $0.60 \mathrm{M} \mathrm{MgCl}_2$, or 200.0 mL of 0.40 M NaCl ?

Iva Lazarova
Iva Lazarova
Numerade Educator
10:25

Problem 26

Calculate the concentration of all ions present in each of the following solutions of strong electrolytes.
a. 0.100 mole of $\mathrm{Ca}\left(\mathrm{NO}_3\right)_2$ in 100.0 mL of solution
b. 2.5 moles of $\mathrm{Na}_2 \mathrm{SO}_4$ in 1.25 L of solution
c. 5.00 g of $\mathrm{NH}_4 \mathrm{Cl}$ in 500.0 mL of solution
d. 1.00 g of $\mathrm{K}_3 \mathrm{PO}_4$ in 250.0 mL of solution

Susan Hallstrom
Susan Hallstrom
Numerade Educator
05:22

Problem 27

Calculate the sodium ion concentration when 70.0 mL of 3.0 M sodium carbonate is added to 30.0 mL of 1.0 M sodium bicarbonate.

Iva Lazarova
Iva Lazarova
Numerade Educator
05:58

Problem 28

A solution is prepared by dissolving 25.0 g of ammonium sulfate in enough water to make 100.0 mL of stock solution. A $10.00-\mathrm{mL}$ sample of this stock solution is added to 50.00 mL of water. Calculate the concentration of ammonium ions and sulfate ions in the final solution.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:06

Problem 29

A standard solution is prepared for the analysis of fluoxymesterone ( $\mathrm{C}_{20} \mathrm{H}_{29} \mathrm{FO}_3$ ), an anabolic steroid. A stock solution is first prepared by dissolving 10.0 mg of fluoxymesterone in enough water to give a total volume of 500.0 mL . A $100.0-\mu \mathrm{L}$ aliquot (portion) of this solution is diluted to a final volume of 100.0 mL . Calculate the concentration of the final solution in terms of molarity.

William Mills
William Mills
Numerade Educator
08:26

Problem 30

A stock solution containing $\mathrm{Mn}^{2+}$ ions is prepared by dissolving 1.584 g of pure manganese metal in nitric acid and diluting to a final volume of 1.000 L . The following solutions are prepared by dilution.
For solution $\mathrm{A}, 50.00 \mathrm{~mL}$ of stock solution is diluted to 1000.0 mL .
For solution $\mathrm{B}, 10.00 \mathrm{~mL}$ of A is diluted to 250.0 mL . For solution $\mathrm{C}, 10.00 \mathrm{~mL}$ of B is diluted to 500.0 mL .
Calculate the molar concentrations of the stock solution and solutions $\mathrm{A}, \mathrm{B}$, and C .

Susan Hallstrom
Susan Hallstrom
Numerade Educator
07:34

Problem 31

The units of parts per million (ppm) and parts per billion (ppb) are commonly used by environmental chemists. In general, 1 ppm means 1 part of solute for every $10^6$ parts of solution. (Both solute and solution are measured using the same units.) Mathematically, by mass:
$$
\mathrm{ppm}=\frac{\mu \mathrm{g} \text { solute }}{\mathrm{g} \text { solution }}=\frac{\mathrm{mg} \text { solute }}{\mathrm{kg} \text { solution }}
$$
In the case of very dilute aqueous solutions, a concentration of 1.0 ppm is equal to $1.0 \mu \mathrm{g}$ of solute per 1.0 mL . of solution, which equals 1.0 g of solution. Parts per billion is defined in a similar fashion. Calculate the molarity of each of the following aqueous solutions.
a. 5.0 ppb Hg in $\mathrm{H}_2 \mathrm{O}$
b. $1.0 \mathrm{ppb} \mathrm{CHCl}_3$ in $\mathrm{H}_2 \mathrm{O}$
c. 10.0 ppm As in $\mathrm{H}_2 \mathrm{O}$
d. 0.10 ppm DDT $\left(\mathrm{C}_{14} \mathrm{H}_9 \mathrm{Cl}_5\right)$ in $\mathrm{H}_2 \mathrm{O}$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
06:17

Problem 32

In the spectroscopic analysis of many substances, a series of standard solutions of known concentration are measured to generate a calibration curve. How would you prepare standard solutions containing 10.0, 25.0, $50.0,75.0$, and 100 . ppm of copper from a commercially produced $1000.0-\mathrm{ppm}$ solution? Assume each solution has a final volume of 100.0 mL . (See Exercise 31 for definitions.)

LJ
Lena Jake
Numerade Educator
02:24

Problem 33

List the formulas of three soluble bromide salts and three insoluble bromide salts. Do the same exercise for sulfate salts, hydroxide salts, and phosphate salts (list three soluble salts and three insoluble salts). List the formulas for six insoluble $\mathrm{Pb}^{2+}$ salts and one soluble $\mathrm{Pb}^{2+}$ salt.

William Mills
William Mills
Numerade Educator
05:18

Problem 34

On the basis of the general solubility rules given in Table 4.1, predict which of the following substances are likely to be soluble in water.
a. zinc chloride
b. lead(II) nitrate
c. lead(II) sulfate
d. sodium iodide
e. cobalt(III) sulfide
f. chromium(III) hydroxide
g. magnesium carbonate
h. ammonium carbonate

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
02:15

Problem 35

A sample may contain any or all of the following ions: $\mathrm{Hg}_2{ }^{2+}, \mathrm{Ba}^{2+}$, and $\mathrm{Mn}^{2+}$.
a. No precipitate formed when an aqueous solution of NaCl was added to the sample solution.
b. No precipitate formed when an aqueous solution of $\mathrm{Na}_2 \mathrm{SO}_4$ was added to the sample solution.
c. A precipitate formed when the sample solution was made basic with NaOH .
Which ion or ions are present in the sample solution?

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
03:28

Problem 36

When 1.0 mole of solid lead nitrate is added to 2.0 moles of aqueous potassium iodide, a yellow precipitate forms. After the precipitate settles to the bottom, does the solution above the precipitate conduct electricity? Explain. Write the complete ionic equation to help you answer this question.

LJ
Lena Jake
Numerade Educator
03:01

Problem 37

When the following solutions are mixed together, what precipitate (if any) will form?
a. $\mathrm{Hg}_2\left(\mathrm{NO}_3\right)_2(a q)+\mathrm{CuSO}_4(a q)$
b. $\mathrm{Ni}\left(\mathrm{NO}_3\right)_2(a q)+\mathrm{CaCl}_2(a q)$
c. $\mathrm{K}_2 \mathrm{CO}_3(a q)+\mathrm{MgI}_2(a q)$
d. $\mathrm{Na}_2 \mathrm{CrO}_4(a q)+\mathrm{AlBr}_3(a q)$

LJ
Lena Jake
Numerade Educator
06:57

Problem 38

For the reactions in Exercise 37, write the balanced molecular equation, complete ionic equation, and net ionic equation. If no precipitate forms, write "No reaction."

Sima Sarker
Sima Sarker
Numerade Educator
10:12

Problem 39

Write the balanced molecular, complete, and net ionic equations for the reaction, if any, that occurs when aqueous solutions of the following are mixed.
a. ammonium sulfate and barium nitrate
b. Iead(II) nitrate and sodium chloride
c. sodium phosphate and potassium nitrate
d. sodium bromide and rubidium chloride
e. copper(II) chloride and sodium hydroxide

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:32

Problem 40

How would you separate the following ions in aqueous solution by selective precipitation?
a. $\mathrm{Ag}^{+}, \mathrm{Ba}^{2+}$, and $\mathrm{Cr}^{3+}$
b. $\mathrm{Ag}^{+}, \mathrm{Pb}^{2+}$, and $\mathrm{Cu}^{2+}$
c. $\mathrm{Hg}_2^{2+}$ and $\mathrm{Ni}^{2+}$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:19

Problem 41

Write the balanced molecular and net ionic equations for the reaction that occurs when the contents of the two beakers are added together. What colors represent the spectator ions in each reaction?
(FIGURE CAN'T COPY)

Susan Hallstrom
Susan Hallstrom
Numerade Educator
06:22

Problem 42

Give an example of how each of the following insoluble ionic compounds could be produced using a precipitation reaction. Write the balanced molecular equation for each reaction.
a. $\mathrm{Fe}(\mathrm{OH})_3(s)$
c. $\mathrm{PbSO}_4(s)$
b. $\mathrm{Hg}_2 \mathrm{Cl}_2(s)$
d. $\mathrm{BaCrO}_4(s)$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:03

Problem 43

Separate samples of a solution of an unknown soluble ionic compound are treated with $\mathrm{KCl}, \mathrm{Na}_2 \mathrm{SO}_4$, and NaOH . A precipitate forms only when $\mathrm{Na}_2 \mathrm{SO}_4$ is added. Which cations could be present in the unknown soluble ionic compound?

William Mills
William Mills
Numerade Educator
04:12

Problem 44

What volume of $0.100 \mathrm{M} \mathrm{Na}_3 \mathrm{PO}_4$ is required to precipitate all of the lead(II) ions from 150.0 mL of 0.250 M $\mathrm{Pb}\left(\mathrm{NO}_3\right)_2$ ?

LJ
Lena Jake
Numerade Educator
11:15

Problem 45

How many grams of silver chloride can be prepared by the reaction of 100.0 mL of 0.20 M silver nitrate with 100.0 mL of 0.15 M calcium chloride? Calculate the concentrations of each ion remaining in solution after precipitation is complete.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
05:00

Problem 46

What mass of solid aluminum hydroxide can be produced when 50.0 mL of $0.200 \mathrm{M} \mathrm{Al}\left(\mathrm{NO}_3\right)_3$ is added to 200.0 mL of 0.100 M KOH ?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:38

Problem 47

What mass of barium sulfate can be produced when 100.0 mL of a $0.100-\mathrm{M}$ solution of barium chloride is mixed with 100.0 mL of a $0.100-\mathrm{M}$ solution of iron(III) sulfate?

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
View

Problem 48

The following drawings represent aqueous solutions. Solution A is 2.00 L of a 2.00 M aqueous solution of copper(II) nitrate. Solution B is 2.00 L of a 3.00 M aqueous solution of potassium hydroxide.
(FIGURE CAN'T COPY)
a. Draw a picture of the solution made by mixing solutions A and B together after the precipitation reaction takes place. Make sure this picture shows the correct relative volume compared with solutions A and B and the correct relative number of ions, along with the correct relative amount of solid formed.
b. Determine the concentrations (in $M$ ) of all ions left in solution (from part a) and the mass of solid formed.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
05:07

Problem 49

What mass of $\mathrm{Na}_2 \mathrm{CrO}_4$ is required to precipitate all of the silver ions from 75.0 mL of a 0.100 M solution of $\mathrm{AgNO}_3$ ?

William Mills
William Mills
Numerade Educator
03:39

Problem 50

A $1.00-\mathrm{g}$ sample of an alkaline earth metal chloride is treated with excess silver nitrate. All of the chloride is recovered as 1.38 g of silver chloride. Identify the metal.

William Mills
William Mills
Numerade Educator
05:58

Problem 51

A mixture contains only NaCl and $\mathrm{Al}_2\left(\mathrm{SO}_4\right)_3$. A $1.45-\mathrm{g}$ sample of the mixture is dissolved in water, and an excess of NaOH is added, producing a precipitate of $\mathrm{Al}(\mathrm{OH})_3$. The precipitate is filtered, dried, and weighed. The mass of the precipitate is 0.107 g . What is the mass percent of $\mathrm{Al}_2\left(\mathrm{SO}_4\right)_3$ in the sample?

LJ
Lena Jake
Numerade Educator
04:01

Problem 52

The thallium (present as $\mathrm{Tl}_2 \mathrm{SO}_4$ ) in a $9.486-\mathrm{g}$ pesticide sample was precipitated as thallium(I) iodide. Calculate the mass percent of $\mathrm{Tl}_2 \mathrm{SO}_4$ in the sample if 0.1824 g of Tll was recovered.

William Mills
William Mills
Numerade Educator
06:21

Problem 53

Saccharin $\left(\mathrm{C}_7 \mathrm{H}_5 \mathrm{NO}_3 \mathrm{~S}\right)$ is sometimes dispensed in tablet form. Ten tablets with a total mass of 0.5894 g were dissolved in water. This solution was then oxidized to convert all the sulfur to sulfate ion, which was precipitated by adding an excess of barium chloride solution. The mass of $\mathrm{BaSO}_4$ obtained was 0.5032 g . What is the average mass of saccharin per tablet? What is the average mass percent of saccharin in the tablets?

LJ
Lena Jake
Numerade Educator
03:54

Problem 54

Douglasite is a mineral with the formula $2 \mathrm{KCl} \cdot \mathrm{FeCl}_2$. $2 \mathrm{H}_2 \mathrm{O}$. Calculate the mass percent of douglasite in a $455.0-\mathrm{mg}$ sample if it took 37.20 mL of a 0.1000 M $\mathrm{AgNO}_3$ solution to precipitate all the $\mathrm{Cl}^{-}$as AgCl . Assume the douglasite is the only source of chloride ion.

Natalie Almond
Natalie Almond
Numerade Educator
04:21

Problem 55

A 1.42-g sample of a pure compound with formula $\mathrm{M}_2 \mathrm{SO}_4$ was dissolved in water and treated with an excess of aqueous calcium chloride, resulting in the precipitation of all the sulfate ions as calcium sulfate. The precipitate was collected, dried, and found to weigh 1.36 g . Determine the atomic mass of M and identify M .

William Mills
William Mills
Numerade Educator
01:06

Problem 56

What is an acid and what is a base? An acid-base reaction is sometimes called a proton-transfer reaction. Explain.

William Mills
William Mills
Numerade Educator
07:30

Problem 57

Write the balanced molecular, complete ionic, and net ionic equations for each of the following acid-base reactions.
a. $\mathrm{HNO}_3(a q)+\mathrm{Al}(\mathrm{OH})_3(s) \rightarrow$
b. $\mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2(a q)+\mathrm{KOH}(a q) \rightarrow$
c. $\mathrm{Ca}(\mathrm{OH})_2(a q)+\mathrm{HCl}(a q) \rightarrow$

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
09:46

Problem 58

Write balanced equations (all three types) for the reactions that occur when the following aqueous solutions are mixed.
a. ammonia (aqueous) and nitric acid
b. barium hydroxide (aqueous) and hydrochloric acid
c. perchloric acid $\left[\mathrm{HClO}_4(\mathrm{aq})\right]$ and solid iron(III) hydroxide
d. solid silver hydroxide and hydrobromic acid

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:54

Problem 59

What acid and what base would react in aqueous solution so that the following salts appear as products in the molecular equation? Write the balanced molecular equation for each reaction.
a. potassium perchlorate
b. cesium nitrate
c. calcium iodide

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:16

Problem 60

Carminic acid, a naturally occurring red pigment extracted from the cochineal insect, contains only carbon, hydrogen, and oxygen. It was commonly used as a dye in the first half of the nineteenth century. It is $53.66 \% \mathrm{C}$ and $4.09 \% \mathrm{H}$ by mass. A titration required 18.02 mL of 0.0406 M NaOH to neutralize 0.3602 g of carminic acid. Assuming that there is only one acidic hydrogen per molecule, what is the molecular formula of carminic acid?

Anand Jangid
Anand Jangid
Numerade Educator
11:54

Problem 61

What volume of each of the following acids will react completely with 50.00 mL of 0.100 M NaOH ?
a. 0.100 M HCl
b. $0.100 \mathrm{M} \mathrm{H}_2 \mathrm{SO}_3$ (two acidic hydrogens)
c. $0.200 \mathrm{M} \mathrm{H}_3 \mathrm{PO}_4$ (three acidic hydrogens)
d. $0.150 \mathrm{M} \mathrm{HNO}_3$
e. $0.200 \mathrm{M} \mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2$ (one acidic hydrogen)
f. $0.300 \mathrm{M} \mathrm{H}_2 \mathrm{SO}_4$ (two acidic hydrogens)

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:12

Problem 62

A $30.0-\mathrm{mL}$ sample of an unknown strong base is neutralized after the addition of 12.0 mL of a $0.150 \mathrm{M} \mathrm{HNO}_3$ solution. If the unknown base concentration is 0.0300 M , give some possible identities for the unknown base.

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
03:42

Problem 63

A student had 1.00 L of a 1.00 M acid solution. Much to the surprise of the student, it took 2.00 L of 1.00 M NaOH solution to react completely with the acid. Explain why it took twice as much NaOH to react with all of the acid.
In a different experiment, a student had 10.0 mL of 0.020 M HCl . Again, much to the surprise of the student, it took only 5.00 mL of 0.020 M strong base to react completely with the HCl . Explain why it took only half as much strong base to react with all of the HCl .

LJ
Lena Jake
Numerade Educator
03:12

Problem 64

Sodium hydroxide solution is usually standardized by titrating a pure sample of potassium hydrogen phthalate $\left(\mathrm{KHC}_8 \mathrm{H}_4 \mathrm{O}_4\right.$, often abbreviated KHP ), an acid with one acidic hydrogen and a molar mass of $204.22 \mathrm{~g} / \mathrm{mol}$. It takes 34.67 mL of a sodium hydroxide solution to titrate a $0.1082-\mathrm{g}$ sample of KHP . What is the molarity of the sodium hydroxide?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
08:11

Problem 65

A $0.500-\mathrm{L}$ sample of $\mathrm{H}_2 \mathrm{SO}_4$ solution was analyzed by taking a $100.0-\mathrm{mL}$ aliquot and adding 50.0 mL of 0.213 M NaOH . After the reaction occurred, an excess of $\mathrm{OH}^{-}$ions remained in the solution. The excess base required 13.21 mL of 0.103 M HCl for neutralization. Calculate the molarity of the original sample of $\mathrm{H}_2 \mathrm{SO}_4$. (Sulfuric acid has two acidic hydrogens.)

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
04:50

Problem 66

What volume of $0.0521 \mathrm{MBa}(\mathrm{OH})_2$ is required to neutralize exactly 14.20 mL of $0.141 \mathrm{M} \mathrm{H}_3 \mathrm{PO}_4$ ? Phosphoric acid contains three acidic hydrogens.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:43

Problem 67

A $10.00-\mathrm{mL}$ sample of vinegar, an aqueous solution of acetic acid $\left(\mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2\right)$, is titrated with 0.5062 M NaOH , and 16.58 mL is required to reach the endpoint.
a. What is the molarity of the acetic acid?
b. If the density of the vinegar is $1.006 \mathrm{~g} / \mathrm{cm}^3$, what is the mass percent of acetic acid in the vinegar?

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
03:43

Problem 68

A student titrates an unknown amount of potassium hydrogen phthalate ( KHP ) with 20.46 mL of a 0.1000 M NaOH solution. KHP (molar mass $=204.22 \mathrm{~g} / \mathrm{mol}$ ) has one acidic hydrogen. How many grams of KHP were titrated (reacted completely) by the sodium hydroxide solution?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
07:06

Problem 69

A student mixes four reagents together, thinking that the solutions will neutralize each other. The solutions mixed together are 50.0 mL of 0.100 M hydrochloric acid, 100.0 mL of 0.200 M of nitric acid, 500.0 mL of 0.0100 M calcium hydroxide, and 200.0 mL of 0.100 M rubidium hydroxide. Is the resulting solution neutral? If not, calculate the concentration of excess $\mathrm{H}^{+}$or $\mathrm{OH}^{-}$ ions left in solution.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:22

Problem 70

A $50.00-\mathrm{mL}$ sample of an ammonia solution is analyzed by titration with HCl . The reaction is
$$
\mathrm{NH}_3(a q)+\mathrm{H}^{+}(a q) \longrightarrow \mathrm{NH}_4{ }^{+}(a q)
$$
It took 39.47 mL of 0.0984 M HCl to titrate (react completely with) the ammonia. What is the concentration of the original ammonia solution?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
06:05

Problem 71

Hydrochloric acid $(75.0 \mathrm{~mL}$ of 0.250 M$)$ is added to 225.0 mL of $0.0550 \mathrm{M} \mathrm{Ba}(\mathrm{OH})_2$ solution. What is the concentration of the excess $\mathrm{H}^{+}$or $\mathrm{OH}^{-}$left in this solution?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:27

Problem 72

A $2.20-\mathrm{g}$ sample of an unknown acid (empirical formula $=\mathrm{C}_3 \mathrm{H}_4 \mathrm{O}_3$ ) is dissolved in 1.0 L of water. A titration required 25.0 mL of 0.500 M NaOH to react completely with all the acid present. Assuming that the unknown acid has one acidic proton per molecule, what is the molecular formula of the unknown acid?

William Mills
William Mills
Numerade Educator
02:14

Problem 73

Differentiate between the following terms.
a. species reduced versus the reducing agent
b. species oxidized versus the oxidizing agent
c. oxidation state versus actual charge

William Mills
William Mills
Numerade Educator
06:17

Problem 74

How do you balance redox reactions by the oxidation states method?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
07:24

Problem 75

Assign oxidation states to all atoms in each compound.
a. $\mathrm{KMnO}_4$
f. $\mathrm{Fe}_3 \mathrm{O}_4$
b. $\mathrm{NiO}_2$
g. $\mathrm{XeOF}_4$
c. $\mathrm{K}_4 \mathrm{Fe}(\mathrm{CN})_6$ (Fe only)
h. $\mathrm{SF}_4$
d. $\left(\mathrm{NH}_4\right)_2 \mathrm{HPO}_4$
i. CO
e. $\mathrm{P}_4 \mathrm{O}_6$
j. $\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:14

Problem 76

Assign oxidation states to all of the following atoms.
a. $\mathrm{UO}_2^{2+}$
d. $\mathrm{As}_4$
g. $\mathrm{Na}_2 \mathrm{~S}_2 \mathrm{O}_3$
b. $\mathrm{As}_2 \mathrm{O}_3$
e. $\mathrm{HAsO}_2$
h. $\mathrm{Hg}_2 \mathrm{Cl}_2$
c. $\mathrm{NaBiO}_3$
f. $\mathrm{Mg}_2 \mathrm{P}_2 \mathrm{O}_7$
i. $\mathrm{Ca}\left(\mathrm{NO}_3\right)_2$

Anand Jangid
Anand Jangid
Numerade Educator
09:16

Problem 77

Assign oxidation states to all of the following atoms.
a. $\mathrm{SrCr}_2 \mathrm{O}_7$
g. $\mathrm{PbSO}_3$
b. $\mathrm{CuCl}_2$
h. $\mathrm{PbO}_2$
c. $\mathrm{O}_2$
i. $\mathrm{Na}_2 \mathrm{C}_2 \mathrm{O}_4$
d. $\mathrm{H}_2 \mathrm{O}_2$
i. $\mathrm{CO}_2$
e. $\mathrm{MgCO}_3$
k. $\left(\mathrm{NH}_4\right)_2 \mathrm{Ce}\left(\mathrm{SO}_4\right)_3$
f. Ag
I. $\mathrm{Cr}_2 \mathrm{O}_3$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
19:01

Problem 78

Tell which of the following are oxidation-reduction reactions. For those that are, identify the oxidizing agent, the reducing agent, the substance being oxidized, and the substance being reduced.
a. $\mathrm{CH}_4(\mathrm{~g})+2 \mathrm{O}_2(\mathrm{~g}) \longrightarrow \mathrm{CO}_2(\mathrm{~g})+2 \mathrm{H}_2 \mathrm{O}(\mathrm{g})$
b. $\mathrm{Zn}(s)+2 \mathrm{HCl}(a q) \longrightarrow \mathrm{ZnCl}_2(a q)+\mathrm{H}_2(g)$
c. $\mathrm{Cr}_2 \mathrm{O}_7^{2-}(a q)+2 \mathrm{OH}^{-}(a q)$
$$
\longrightarrow 2 \mathrm{CrO}_4^{2-}(a q)+\mathrm{H}_2 \mathrm{O}(l)
$$
d. $\mathrm{O}_3(\mathrm{~g})+\mathrm{NO}(\mathrm{g}) \longrightarrow \mathrm{O}_2(\mathrm{~g})+\mathrm{NO}_2(\mathrm{~g})$
e. $2 \mathrm{H}_2 \mathrm{O}_2(l) \longrightarrow 2 \mathrm{H}_2 \mathrm{O}(l)+\mathrm{O}_2(\mathrm{~g})$
f. $2 \mathrm{CuCl}(a q) \longrightarrow \mathrm{CuCl}_2(a q)+\mathrm{Cu}(s)$
g. $\mathrm{HCl}(\mathrm{g})+\mathrm{NH}_3(\mathrm{~g}) \longrightarrow \mathrm{NH}_4 \mathrm{Cl}(\mathrm{s})$
h. $\mathrm{SiCl}_4(l)+2 \mathrm{H}_2 \mathrm{O}(l) \longrightarrow 4 \mathrm{HCl}(a q)+\mathrm{SiO}_2(s)$
i. $\mathrm{SiCl}_4(l)+2 \mathrm{Mg}(s) \longrightarrow 2 \mathrm{MgCl}_2(s)+\mathrm{Si}(s)$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
10:05

Problem 79

Many oxidation-reduction reactions can be balanced by inspection. Try to balance the following reactions by inspection. In each reaction, identify the substance reduced and the substance oxidized.
a. $\mathrm{Al}(\mathrm{s})+\mathrm{HCl}(a q) \longrightarrow \mathrm{AlCl}_3(a q)+\mathrm{H}_2(g)$
b. $\mathrm{CH}_4(\mathrm{~g})+\mathrm{S}(\mathrm{s}) \longrightarrow \mathrm{CS}_2(\mathrm{l})+\mathrm{H}_2 \mathrm{~S}(\mathrm{~g})$
c. $\mathrm{C}_3 \mathrm{H}_8(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \longrightarrow \mathrm{CO}_2(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(\mathrm{l})$
d. $\mathrm{Cu}(s)+\mathrm{Ag}^{+}(a q) \longrightarrow \mathrm{Ag}(s)+\mathrm{Cu}^{2+}(a q)$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
08:45

Problem 80

Balance each of the following oxidation-reduction reactions by using the oxidation states method.
a. $\mathrm{C}_2 \mathrm{H}_6(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \longrightarrow \mathrm{CO}_2(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(\mathrm{g})$
b. $\mathrm{Mg}(s)+\mathrm{HCl}(a q) \longrightarrow \mathrm{Mg}^{2+}(a q)+\mathrm{Cl}^{-}(a q)+\mathrm{H}_2(g)$
c. $\mathrm{Cu}(s)+\mathrm{Ag}^{+}(a q) \longrightarrow \mathrm{Cu}^{2+}(a q)+\mathrm{Ag}(s)$
d. $\mathrm{Zn}(s)+\mathrm{H}_2 \mathrm{SO}_4(a q) \longrightarrow \mathrm{ZnSO}_4(a q)+\mathrm{H}_2(g)$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
29:48

Problem 81

Balance the following oxidation-reduction reactions, which occur in acidic solution, using the half-reaction method.
a. $\mathrm{Cu}(s)+\mathrm{NO}_3^{-}(a q) \longrightarrow \mathrm{Cu}^{2+}(a q)+\mathrm{NO}(g)$
b. $\mathrm{Cr}_2 \mathrm{O}_7^{2-}(a q)+\mathrm{Cl}^{-}(a q) \longrightarrow \mathrm{Cr}^{3+}(a q)+\mathrm{Cl}_2(g)$
c. $\mathrm{Pb}(s)+\mathrm{PbO}_2(s)+\mathrm{H}_2 \mathrm{SO}_4(a q) \longrightarrow \mathrm{PbSO}_4(s)$
d. $\mathrm{Mn}^{2+}(a q)+\mathrm{NaBiO}_3(s) \longrightarrow \mathrm{Bi}^{3+}(a q)+\mathrm{MnO}_4{ }^{-}(a q)$
e. $\mathrm{H}_3 \mathrm{AsO}_4(a q)+\mathrm{Zn}(s) \longrightarrow \mathrm{AsH}_3(g)+\mathrm{Zn}^{2+}(a q)$
f. $\mathrm{As}_2 \mathrm{O}_3(s)+\mathrm{NO}_3^{-}(a q) \longrightarrow \mathrm{H}_3 \mathrm{AsO}_4(a q)+\mathrm{NO}(g)$
g. $\mathrm{Br}^{-}(a q)+\mathrm{MnO}_4^{-}(a q) \longrightarrow \mathrm{Br}_2(l)+\mathrm{Mn}^{2+}(a q)$
h. $\mathrm{CH}_3 \mathrm{OH}(a q)+\mathrm{Cr}_2 \mathrm{O}_7^{2-}(a q)$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
25:28

Problem 82

Balance the following oxidation-reduction reactions, which occur in basic solution, using the half-reaction method.
a. $\mathrm{Al}(s)+\mathrm{MnO}_4{ }^{-}(a q) \longrightarrow \mathrm{MnO}_2(s)+\mathrm{Al}(\mathrm{OH})_4{ }^{-}(a q)$
b. $\mathrm{Cl}_2(g) \longrightarrow \mathrm{Cl}^{-}(a q)+\mathrm{ClO}^{-}(a q)$
c. $\mathrm{NO}_2^{-}(a q)+\mathrm{Al}(s) \longrightarrow \mathrm{NH}_3(g)+\mathrm{AlO}_2^{-}(a q)$
d. $\mathrm{MnO}_4^{-}(a q)+\mathrm{S}^{2-}(a q) \longrightarrow \mathrm{MnS}(s)+\mathrm{S}(s)$
e. $\mathrm{CN}^{-}(a q)+\mathrm{MnO}_4^{-}(a q) \longrightarrow \mathrm{CNO}^{-}(a q)+\mathrm{MnO}_2(s)$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
31:26

Problem 83

Balance the following equations by the half-reaction method.
a. $\mathrm{Fe}(s)+\mathrm{HCl}(a q) \longrightarrow \mathrm{HFeCl}_4(a q)+\mathrm{H}_2(g)$
b. $\mathrm{IO}_3{ }^{-}(a q)+\mathrm{I}^{-}(a q) \xrightarrow{\text { Acidic }} \mathrm{I}_3{ }^{-}(a q)$
c. $\mathrm{Cr}(\mathrm{NCS})_6{ }^{4-}(a q)+\mathrm{Ce}^{4+}(a q)$
$$
\begin{aligned}
\xrightarrow{\text { Acddic }} & \mathrm{Cr}^{3+}(a q)+\mathrm{Ce}^{3+}(a q)+\mathrm{NO}_3{ }^{-}(a q) \\
& +\mathrm{CO}_2(g)+\mathrm{SO}_4{ }^{2-}(a q)
\end{aligned}
$$
d. $\mathrm{CrI}_3(s)+\mathrm{Cl}_2(\mathrm{~g})$
$$
\xrightarrow{\text { Basic }} \mathrm{CrO}_4{ }^{2-}(a q)+\mathrm{IO}_4{ }^{-}(a q)+\mathrm{Cl}^{-}(a q)
$$
e. $\mathrm{Fe}(\mathrm{CN})_6{ }^{4-}(a q)+\mathrm{Ce}^{4+}(a q)$
$$
\begin{aligned}
\xrightarrow{\text { Basic }} & \mathrm{Ce}(\mathrm{OH})_3(s)+\mathrm{Fe}(\mathrm{OH})_3(s)+\mathrm{CO}_3{ }^{2-}(a q) \\
& +\mathrm{NO}_3^{-}(a q)
\end{aligned}
$$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
21:06

Problem 84

One of the classic methods for the determination of the manganese content in steel involves converting all the manganese to the deeply colored permanganate ion and then measuring the absorption of light. The steel is first dissolved in nitric acid, producing the manganese(II) ion and nitrogen dioxide gas. This solution is then reacted with an acidic solution containing periodate ion; the products are the permanganate and iodate ions. Write balanced chemical equations for both of these steps.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
08:08

Problem 85

A solution of permanganate is standardized by titration with oxalic acid $\left(\mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4\right)$. It required 28.97 mL of the permanganate solution to react completely with 0.1058 g of oxalic acid. The unbalanced equation for the reaction is
$$
\mathrm{MnO}_4^{-}(a q)+\mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4(a q) \xrightarrow{\text { Aadic }} \mathrm{Mn}^{2+}(a q)+\mathrm{CO}_2(g)
$$
What is the molarity of the permanganate solution?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
14:13

Problem 86

A $50.00-\mathrm{mL}$ sample of solution containing $\mathrm{Fe}^{2+}$ ions is titrated with a $0.0216 \mathrm{M} \mathrm{KMnO}_4$ solution. It required 20.62 mL of $\mathrm{KMnO}_4$ solution to oxidize all the $\mathrm{Fe}^{2+}$ ions to $\mathrm{Fe}^{3+}$ ions by the reaction
$$
\mathrm{MnO}_4^{-}(a q)+\mathrm{Fe}^{2+}(a q) \xrightarrow{\text { Acidcc }} \mathrm{Mn}^{2+}(a q)+\mathrm{Fe}^{3+}(a q)
$$
(Unbalanced)
a. What was the concentration of $\mathrm{Fe}^{2+}$ ions in the sample solution?
b. What volume of $0.0150 \mathrm{M} \mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ solution would it take to do the same titration? The reaction is
$$
\mathrm{Cr}_2 \mathrm{O}_7^{2-}(a q)+\mathrm{Fe}^{2+}(a q) \xrightarrow{\text { Acidic }} \mathrm{Cr}^{3+}(a q)+\mathrm{Fe}^{3+}(a q)
$$
(Unbalanced)

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:10

Problem 87

The iron content of iron ore can be determined by titration with a standard $\mathrm{KMnO}_4$ solution. The iron ore is dissolved in HCl , and all the iron is reduced to $\mathrm{Fe}^{2+}$ ions. This solution is then titrated with $\mathrm{KMnO}_4$ solution, producing $\mathrm{Fe}^{3+}$ and $\mathrm{Mn}^{2+}$ ions in acidic solution. If it required 38.37 mL of $0.0198 \mathrm{M} \mathrm{KMnO}_4$ to titrate a solution made from 0.6128 g of iron ore, what is the mass percent of iron in the iron ore?

LJ
Lena Jake
Numerade Educator
10:53

Problem 88

The vanadium in a sample of ore is converted to $\mathrm{VO}^{2+}$. The $\mathrm{VO}^{2+}$ ion is subsequently titrated with $\mathrm{MnO}_4^{-}$in acidic solution to form $\mathrm{V}(\mathrm{OH})_4{ }^{+}$and manganese(II) ion. To titrate the solution, 26.45 mL of $0.02250 \mathrm{M} \mathrm{MnO}_4^{-}$ was required. If the mass percent of vanadium in the ore was $58.1 \%$, what was the mass of the ore sample?

LJ
Lena Jake
Numerade Educator
06:35

Problem 89

When hydrochloric acid reacts with magnesium metal, hydrogen gas and aqueous magnesium chloride are produced. What volume of 5.0 M HCl is required to react completely with 3.00 g of magnesium?

LJ
Lena Jake
Numerade Educator
08:21

Problem 90

Triiodide ions are generated in solution by the following (unbalanced) reaction in acidic solution:
$$
\mathrm{IO}_3^{-}(a q)+\mathrm{I}^{-}(a q) \longrightarrow \mathrm{I}_3^{-}(a q)
$$
Triodide ion is determined by titration with a sodium thiosulfate $\left(\mathrm{Na}_2 \mathrm{~S}_2 \mathrm{O}_3\right)$ solution. The products are iodide ion and tetrathionate ion $\left(\mathrm{S}_4 \mathrm{O}_6{ }^{2-}\right)$.
a. Balance the equation for the reaction of $\mathrm{OO}_3^{-}$with $\mathrm{I}^{-}$ions.
b. A sample of 0.6013 g of potassium iodate was dissolved in water. Hydrochloric acid and solid potassium iodide were then added in excess. What is the minimum mass of solid KI and the minimum volume of 3.00 M HCl required to convert all of the $\mathrm{IO}_3^{-}$ions to $\mathrm{I}_3^{-}$ions?
c. Write and balance the equation for the reaction of $\mathrm{S}_2 \mathrm{O}_3{ }^{2-}$ with $\mathrm{I}_3^{-}$in acidic solution.
d. A $25.00-\mathrm{mL}$ sample of a 0.0100 M solution of $\mathrm{KIO}_3$ is reacted with an excess of KI . It requires 32.04 mL of $\mathrm{Na}_2 \mathrm{~S}_2 \mathrm{O}_3$ solution to titrate the $\mathrm{I}_3{ }^{-}$ions present. What is the molarity of the $\mathrm{Na}_2 \mathrm{~S}_2 \mathrm{O}_3$ solution?
e. How would you prepare 500.0 mL of the $\mathrm{KIO}_3$ solution in part d, using pure, dry $\mathrm{KIO}_3$ ?

Ronald Prasad
Ronald Prasad
Numerade Educator
04:43

Problem 91

A 230 .-mL sample of a $0.275 \mathrm{M} \mathrm{CaCl}_2$ solution is left on a hot plate overnight; the following morning, the solution is 1.10 M . What volume of water evaporated from the $0.275 \mathrm{M} \mathrm{CaCl}_2$ solution?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:06

Problem 92

Using the general solubility rules given in Table 4.1, name three reagents that would form precipitates with each of the following ions in aqueous solution. Write the net ionic equation for each of your suggestions.
a. chloride ion
d. sulfate ion
b. calcium ion
e. mercury(I) ion, $\mathrm{Hg}_2{ }^{2+}$
c. iron(III) ion
f. silver ion

Lottie Adams
Lottie Adams
Numerade Educator
04:54

Problem 93

Consider a $1.50-\mathrm{g}$ mixture of magnesium nitrate and magnesium chloride. After dissolving this mixture in water, 0.500 M silver nitrate is added dropwise until precipitate formation is complete. This mass of the white precipitate formed is 0.641 g .
a. Calculate the mass percent of magnesium chloride in the mixture.
b. Determine the minimum volume of silver nitrate that must have been added to ensure complete formation of the precipitate.

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
03:16

Problem 94

Suppose 50.0 mL of $0.250 \mathrm{M} \mathrm{CoCl}_2$ solution is added to 25.0 mL of $0.350 \mathrm{M} \mathrm{NiCl}_2$ solution. Calculate the concentration, in moles per liter, of each of the ions present after mixing. Assume that the volumes are additive.

LJ
Lena Jake
Numerade Educator
10:48

Problem 95

In most of its ionic compounds, cobalt is either Co (II) or Co (III). One such compound, containing chloride ion and waters of hydration, was analyzed, and the following results were obtained. A 0.256 -g sample of the compound was dissolved in water, and excess silver nitrate was added. The silver chloride was filtered, dried, and weighed, and it had a mass of 0.308 g . A second sample of 0.416 g of the compound was dissolved in water, and an excess of sodium hydroxide was added. The hydroxide salt was filtered and heated in a flame, forming cobalt(III) oxide. The mass of the cobalt(III) oxide formed was 0.145 g .
a. What is the percent composition, by mass, of the compound?
b. Assuming the compound contains one cobalt ion per formula unit, what is the formula?
c. Write balanced equations for the three reactions described.

William Mills
William Mills
Numerade Educator
04:44

Problem 96

A mixture contains only NaCl and $\mathrm{Fe}\left(\mathrm{NO}_3\right)_3$. $\mathrm{A} 0.456-\mathrm{g}$ sample of the mixture is dissolved in water, and an excess of NaOH is added, producing a precipitate of $\mathrm{Fe}(\mathrm{OH})_3$. The precipitate is filtered, dried, and weighed. Its mass is 0.107 g . Calculate the following.
a. the mass of iron in the sample
b. the mass of $\mathrm{Fe}\left(\mathrm{NO}_3\right)_3$ in the sample
c. the mass percent of $\mathrm{Fe}\left(\mathrm{NO}_3\right)_3$ in the sample

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
04:13

Problem 97

A mixture contains only sodium chloride and potassium chloride. A $0.1586-\mathrm{g}$ sample of the mixture was dissolved in water. It took 22.90 mL of $0.1000 \mathrm{M} \mathrm{AgNO}_3$ to completely precipitate all the chloride present. What is the composition (by mass percent) of the mixture?

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
09:04

Problem 98

Tris(pentafluorophenyl)borane, commonly known by its acronym BARF, is frequently used to initiate polymerization of ethylene or propylene in the presence of a catalytic transition metal compound. It is composed solely of $\mathrm{C}, \mathrm{F}$, and B ; it is $42.23 \% \mathrm{C}$ and $55.66 \% \mathrm{~F}$ by mass.
a. What is the empirical formula of BARF?
b. A 2.251-g sample of BARF dissolved in 347.0 mL . of solution produces a 0.01267 M solution. What is the molecular formula of BARF?

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
06:32

Problem 99

A student added 50.0 mL of an NaOH solution to 100.0 mL of 0.400 M HCl . The solution was then treated with an excess of aqueous chromium(III) nitrate, resulting in formation of 2.06 g of precipitate. Determine the concentration of the NaOH solution.

William Mills
William Mills
Numerade Educator
09:11

Problem 100

In a 1-L beaker, 203 mL of 0.307 M ammonium chromate was mixed with 137 mL of 0.269 M chromium(III) nitrite to produce ammonium nitrite and chromium(III) chromate. Write the balanced chemical equation for the reaction occurring here. If the percent yield of the reaction was $88.0 \%$, how much chromium(III) chromate was isolated?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
06:07

Problem 101

It took $25.06 \pm 0.05 \mathrm{~mL}$ of a sodium hydroxide solution to titrate a $0.4016-\mathrm{g}$ sample of KHP (see Exercise 64). Calculate the concentration and uncertainty in the concentration of the sodium hydroxide solution. (See Appendix Section A1.5.) Neglect any uncertainty in the mass.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:38

Problem 102

You wish to prepare 1 L of a 0.02 M potassium iodate solution. You require that the final concentration be within $1 \%$ of 0.02 M and that the concentration must be known precisely to the fourth decimal place. How would you prepare this solution? Specify the glassware you would use, the precision needed for the balance, and the ranges of acceptable masses of $\mathrm{KIO}_3$ that can be used.

William Mills
William Mills
Numerade Educator
04:09

Problem 103

Citric acid, which can be obtained from lemon juice, has the molecular formula $\mathrm{C}_6 \mathrm{H}_8 \mathrm{O}_7$. A $0.250-\mathrm{g}$ sample of citric acid dissolved in 25.0 mL of water requires 37.2 mL of 0.105 M NaOH for complete neutralization. How many acidic hydrogens per molecule does citric acid have?

William Mills
William Mills
Numerade Educator
03:11

Problem 104

Acetylsalicylic acid is the active ingredient in aspirin. It took 35.17 mL of 0.5065 M sodium hydroxide to react completely with 3.210 g of acetylsalicylic acid. Acetylsalicylic acid has one acidic hydrogen. What is the molar mass of acetylsalicylic acid?

William Mills
William Mills
Numerade Educator
01:46

Problem 105

A 6.50-g sample of a diprotic acid requires 137.5 mL of a 0.750 M NaOH solution for complete neutralization. Determine the molar mass of the acid.

LJ
Lena Jake
Numerade Educator
08:11

Problem 106

Some of the substances commonly used in stomach antacids are $\mathrm{MgO}, \mathrm{Mg}(\mathrm{OH})_2$, and $\mathrm{Al}(\mathrm{OH})_3$.
a. Write a balanced equation for the neutralization of hydrochloric acid by each of these substances.
b. Which of these substances will neutralize the greatest amount of 0.10 M HCl per gram?

LJ
Lena Jake
Numerade Educator
04:08

Problem 107

Chlorisondamine chloride $\left(\mathrm{C}_{14} \mathrm{H}_{20} \mathrm{Cl}_6 \mathrm{~N}_2\right)$ is a drug used in the treatment of hypertension. A 1.28 -g sample of a medication containing the drug was treated to destroy the organic material and to release all the chlorine as chloride ion. When the filtered solution containing chloride ion was treated with an excess of silver nitrate, 0.104 g silver chloride was recovered. Calculate the mass percent of chlorisondamine chloride in the medication, assuming the drug is the only source of chloride.

William Mills
William Mills
Numerade Educator
02:19

Problem 108

Calculate the concentration of all ions present when 0.160 g of $\mathrm{MgCl}_2$ is dissolved in 100.0 mL of solution.

LJ
Lena Jake
Numerade Educator
02:44

Problem 109

A solution is prepared by dissolving 0.6706 g oxalic acid $\left(\mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4\right)$ in enough water to make 100.0 mL of solution. A $10.00-\mathrm{mL}$ aliquot (portion) of this solution is then diluted to a final volume of 250.0 mL . What is the final molarity of the oxalic acid solution?

William Mills
William Mills
Numerade Educator
06:02

Problem 110

For the following chemical reactions, determine the precipitate produced when the two reactants listed below are mixed together. Indicate "none" if no precipitate will form.
(FIGURE CAN'T COPY)

LJ
Lena Jake
Numerade Educator
02:55

Problem 111

What volume of 0.100 M NaOH is required to precipitate all of the nickel(II) ions from 150.0 mL of a $0.249-\mathrm{M}$ solution of $\mathrm{Ni}\left(\mathrm{NO}_3\right)_2$ ?

Natalie Almond
Natalie Almond
Numerade Educator
04:34

Problem 112

A $500.0-\mathrm{mL}$ sample of 0.200 M sodium phosphate is mixed with 400.0 mL of 0.289 M barium chloride. What is the mass of the solid produced?

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
04:11

Problem 113

A $450.0-\mathrm{mL}$ sample of a $0.257-\mathrm{M}$ solution of silver nitrate is mixed with 400.0 mL of 0.200 M calcium chloride. What is the concentration of $\mathrm{Cl}^{-}$in solution after the reaction is complete?

William Mills
William Mills
Numerade Educator
04:39

Problem 114

The zinc in a $1.343-\mathrm{g}$ sample of a foot powder was precipitated as $\mathrm{ZnNH}_4 \mathrm{PO}_4$. Strong heating of the precipitate yielded $0.4089 \mathrm{~g} \mathrm{Zn}_2 \mathrm{P}_2 \mathrm{O}_7$. Calculate the mass percent of zinc in the sample of foot powder.

LJ
Lena Jake
Numerade Educator
02:41

Problem 115

A $50.00-\mathrm{mL}$ sample of aqueous $\mathrm{Ca}(\mathrm{OH})_2$ requires 34.66 mL of a $0.944-\mathrm{M}$ nitric acid for neutralization. Calculate the concentration (molarity) of the original solution of calcium hydroxide.

William Mills
William Mills
Numerade Educator
03:33

Problem 116

When organic compounds containing sulfur are burned, sulfur dioxide is produced. The amount of $\mathrm{SO}_2$ formed can be determined by the reaction with hydrogen peroxide:
$$
\mathrm{H}_2 \mathrm{O}_2(a q)+\mathrm{SO}_2(\mathrm{~g}) \longrightarrow \mathrm{H}_2 \mathrm{SO}_4(a q)
$$
The resulting sulfuric acid is then titrated with a standard NaOH solution. A 1.302-g sample of coal is burned and the $\mathrm{SO}_2$ is collected in a solution of hydrogen peroxide. It took 28.44 mL of a $0.1000-\mathrm{M} \mathrm{NaOH}$ solution to titrate the resulting sulfuric acid. Calculate the mass percent of sulfur in the coal sample. Sulfuric acid has two acidic hydrogens.

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
05:17

Problem 117

Assign the oxidation state for the element listed in each of the following compounds:
(FIGURE CAN'T COPY)

Tom Rutherford
Tom Rutherford
Numerade Educator
00:52

Problem 118

The blood alcohol $\left(\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}\right)$ level can be determined by titrating a sample of blood plasma with an acidic potassium dichromate solution, resulting in the production of $\mathrm{Cr}^{3+}(\mathrm{aq})$ and carbon dioxide. The reaction can be monitored because the dichromate ion $\left(\mathrm{Cr}_2 \mathrm{O}_7{ }^{2-}\right)$ is orange in solution, and the $\mathrm{Cr}^{3+}$ ion is green. The unbalanced redox equation is
$$
\mathrm{Cr}_2 \mathrm{O}_7^{2-}(a q)+\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}(a q) \longrightarrow \mathrm{Cr}^{3+}(a q)+\mathrm{CO}_2(g)
$$
If 31.05 mL of 0.0600 M potassium dichromate solution is required to titrate 30.0 g of blood plasma, determine the mass percent of alcohol in the blood.

David Collins
David Collins
Numerade Educator
04:51

Problem 119

Zinc and magnesium metal each react with hydrochloric acid according to the following equations:
$$
\begin{gathered}
\mathrm{Zn}(s)+2 \mathrm{HCl}(a q) \longrightarrow \mathrm{ZnCl}_2(a q)+\mathrm{H}_2(g) \\
\mathrm{Mg}(s)+2 \mathrm{HCl}(a q) \longrightarrow \mathrm{MgCl}_2(a q)+\mathrm{H}_2(g)
\end{gathered}
$$
A $10.00-\mathrm{g}$ mixture of zinc and magnesium is reacted with the stoichiometric amount of hydrochloric acid. The reaction mixture is then reacted with 156 mL of 3.00 M silver nitrate to produce the maximum possible amount of silver chloride.
a. Determine the percent magnesium by mass in the original mixture.
b. If 78.0 mL of HCl was added, what was the concentration of the HCl ?

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
06:05

Problem 120

A $10.00-\mathrm{g}$ sample consisting of a mixture of sodium chloride and potassium sulfate is dissolved in water. This aqueous mixture then reacts with excess aqueous lead(II) nitrate to form 21.75 g of solid. Determine the mass percent of sodium chloride in the original mixture.

LJ
Lena Jake
Numerade Educator
02:59

Problem 121

Consider the reaction of 19.0 g of zinc with excess silver nitrite to produce silver metal and zinc nitrite. The reaction is stopped before all the zinc metal has reacted and 29.0 g of solid metal is present. Calculate the mass of each metal in the 29.0 -g mixture.

William Mills
William Mills
Numerade Educator
06:23

Problem 122

Consider an experiment in which two burets, Y and Z , are simultaneously draining into a beaker that initially contained 275.0 mL of 0.300 M HCl . Buret Y contains 0.150 M NaOH and buret Z contains 0.250 M KOH . The stoichiometric point in the titration is reached 60.65 minutes after Y and Z were started simultaneously. The total volume in the beaker at the stoichiometric point is 655 mL . Calculate the flow rates of burets Y and Z . Assume the flow rates remain constant during the experiment.

William Mills
William Mills
Numerade Educator
08:30

Problem 123

A sample is a mixture of KCl and KBr . When 0.1024 g of the sample is dissolved in water and reacted with excess silver nitrate, 0.1889 g of solid is obtained. What is the composition by mass percent of the mixture?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:23

Problem 124

You made 100.0 mL of a lead(II) nitrate solution for lab but forgot to cap it. The next lab session you noticed that there was only 80.0 mL left (the rest had evaporated). In addition, you forgot the initial concentration of the solution. You decide to take 2.00 mL of the solution and add an excess of a concentrated sodium chloride solution. You obtain a solid with a mass of 3.407 g . What was the concentration of the original lead(II) nitrate solution?

William Mills
William Mills
Numerade Educator
05:07

Problem 125

Polychlorinated biphenyls (PCBs) have been used extensively as dielectric materials in electrical transformers. Because PCBs have been shown to be potentially harmful, analysis for their presence in the environment has become very important. PCBs are manufactured according to the following generic reaction:
$$
\mathrm{C}_{12} \mathrm{H}_{10}+n \mathrm{Cl}_2 \xrightarrow[\text { catalyst }]{\mathrm{Fe}} \mathrm{C}_{12} \mathrm{H}_{10-n} \mathrm{Cl}_n+n \mathrm{HCl}
$$
This reaction results in a mixture of PCB products. The mixture is analyzed by decomposing the PCBs and then precipitating the resulting $\mathrm{Cl}^{-}$as AgCl .
a. Develop a general equation that relates the average value of $n$ to the mass of a given mixture of PCBs and the mass of AgCl produced.
b. A $0.1947-\mathrm{g}$ sample of a commercial PCB yielded 0.4971 g of AgCl . What is the average value of $n$ for this sample?

Mehrnaz Siavoshi
Mehrnaz Siavoshi
Numerade Educator
07:19

Problem 126

Consider reacting copper(II) sulfate with iron. Two possible reactions can occur, as represented by the following equations.
$$
\text { copper(II) sulfate }(a q)+\text { iron(s) } \underset{\text { copper(s) }}{\longrightarrow}+\text { iron(II) sulfate }(a q)
$$
$$
\text { copper(II) sulfate }(a q)+\text { iron(s) } \longrightarrow \text { copper(s) }+ \text { iron(III) sulfate }(a q)
$$
You place 87.7 mL of a 0.500 M solution of copper(II) sulfate in a beaker. You then add 2.00 g of iron filings to the copper(II) sulfate solution. After the reaction occurs, you isolate 2.27 g of copper. Which equation above describes the reaction that occurred? Support your answer.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
23:41

Problem 127

A stream flows at a rate of $5.00 \times 10^4$ liters per second ( $\mathrm{L} / \mathrm{s}$ ) upstream of a manufacturing plant. The plant discharges $3.50 \times 10^3 \mathrm{~L} / \mathrm{s}$ of water that contains 65.0 ppm HCl into the stream. (See Exercise 31 for definitions.)
a. Calculate the stream's total flow rate downstream from this plant.
b. Calculate the concentration of HCl in ppm downstream from this plant.
c. Further downstream, another manufacturing plant diverts $1.80 \times 10^4 \mathrm{~L} / \mathrm{s}$ of water from the stream for its own use. This plant must first neutralize the acid and does so by adding lime:
$$
\mathrm{CaO}(s)+2 \mathrm{H}^{+}(a q) \longrightarrow \mathrm{Ca}^{2+}(a q)+\mathrm{H}_2 \mathrm{O}(l)
$$
What mass of CaO is consumed in an 8.00 -h work day by this plant?
d. The original stream water contained 10.2 ppm $\mathrm{Ca}^{2+}$. Although no calcium was in the waste water from the first plant, the waste water of the second plant contains $\mathrm{Ca}^{2+}$ from the neutralization process. If $90.0 \%$ of the water used by the second plant is returned to the stream, calculate the concentration of $\mathrm{Ca}^{2+}$ in ppm downstream of the second plant.

Ethan Fuhrman
Ethan Fuhrman
Numerade Educator
06:50

Problem 128

Chromium has been investigated as a coating for steel cans. The thickness of the chromium film is determined by dissolving a sample of a can in acid and oxidizing the resulting $\mathrm{Cr}^{3+}$ to $\mathrm{Cr}_2 \mathrm{O}_7^{2-}$ with the peroxydisulfate ion:
$$
\begin{aligned}
\mathrm{S}_2 \mathrm{O}_8^{2-}(a q)+\mathrm{Cr}^{3+}(a q) & +\mathrm{H}_2 \mathrm{O}(l) \longrightarrow \mathrm{Cr}_2 \mathrm{O}_7^{2-}(a q) \\
+ & \mathrm{SO}_4^{2-}(a q)+\mathrm{H}^{+}(a q) \text { (Unbalanced) }
\end{aligned}
$$
After removal of unreacted $\mathrm{S}_2 \mathrm{O}_8{ }^{2-}$, an excess of ferrous ammonium sulfate $\left[\mathrm{Fe}\left(\mathrm{NH}_4\right)_2\left(\mathrm{SO}_4\right)_2 \cdot 6 \mathrm{H}_2 \mathrm{O}\right]$ is added, reacting with $\mathrm{Cr}_2 \mathrm{O}_7^{2-}$ produced from the first reaction. The unreacted $\mathrm{Fe}^{2+}$ from the excess ferrous ammonium sulfate is titrated with a separate $\mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ solution. The reaction is:
$$
\begin{aligned}
\mathrm{H}^{+}(a q)+\mathrm{Fe}^{2+}(a q)+ & \mathrm{Cr}_2 \mathrm{O}_7^{2-}(a q) \longrightarrow \mathrm{Fe}^{3+}(a q) \\
+ & \mathrm{Cr}^{3+}(a q)+\mathrm{H}_2 \mathrm{O}(l) \text { (Unbalanced) }
\end{aligned}
$$
a. Write balanced chemical equations for the two reactions.
b. In one analysis, a $40.0-\mathrm{cm}^2$ sample of a chromiumplated can was treated according to this procedure. After dissolution and removal of excess $\mathrm{S}_2 \mathrm{O}_8{ }^{2-}$, 3.000 g of $\mathrm{Fe}\left(\mathrm{NH}_4\right)_2\left(\mathrm{SO}_4\right)_2 \cdot 6 \mathrm{H}_2 \mathrm{O}$ was added. It took 8.58 mL of $0.0520 \mathrm{M} \mathrm{K}_2 \mathrm{Cr}_2 \mathrm{O}_7$ solution to completely react with the excess $\mathrm{Fe}^{2+}$. Calculate the thickness of the chromium film on the can. (The density of chromium is $7.19 \mathrm{~g} / \mathrm{cm}^3$.)

Ronald Prasad
Ronald Prasad
Numerade Educator
04:35

Problem 129

You are given a solid that is a mixture of $\mathrm{Na}_2 \mathrm{SO}_4$ and $\mathrm{K}_2 \mathrm{SO}_4$. A $0.205-\mathrm{g}$ sample of the mixture is dissolved in water. An excess of an aqueous solution of $\mathrm{BaCl}_2$ is added. The $\mathrm{BaSO}_4$ that is formed is filtered, dried, and weighed. Its mass is 0.298 g . What mass of $\mathrm{SO}_4{ }^{2-}$ ion is in the sample? What is the mass percent of $\mathrm{SO}_4{ }^{2-}$ ion in the sample? What are the percent compositions by mass of $\mathrm{Na}_2 \mathrm{SO}_4$ and $\mathrm{K}_2 \mathrm{SO}_4$ in the sample?

William Mills
William Mills
Numerade Educator
09:00

Problem 130

Three students were asked to find the identity of the metal in a particular sulfate salt. They dissolved a 0.1472 -g sample of the salt in water and treated it with excess barium chloride, resulting in the precipitation of barium sulfate. After the precipitate had been filtered and dried, it weighed 0.2327 g .
Each student analyzed the data independently and came to different conclusions. Pat decided that the metal was titanium. Chris thought it was sodium. Randy re-
ported that it was gallium. What formula did each student assign to the sulfate salt?
Look for information on the sulfates of gallium, sodium, and titanium in this text and reference books such as the CRC Handbook of Chemistry and Physics. What further tests would you suggest to determine which student is most likely correct?

Ronald Prasad
Ronald Prasad
Numerade Educator
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Problem 131

A sample is a mixture of $\mathrm{AgNO}_3, \mathrm{CuCl}_2$, and $\mathrm{FeCl}_3$. When a $1.0000-\mathrm{g}$ sample of the mixture is dissolved in water and reacted with excess silver nitrate, 1.7809 g of precipitate forms. When a separate $1.0000-\mathrm{g}$ sample of the mixture is treated with a reducing agent, all the metal ions in the mixture are reduced to pure metals. The total mass of pure metals produced is 0.4684 g . Calculate the mass percent of $\mathrm{AgNO}_3, \mathrm{CuCl}_2$, and $\mathrm{FeCl}_3$ in the original mixture.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
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Problem 132

One high-temperature superconductor has the general formula $\mathrm{YBa}_2 \mathrm{Cu}_3 \mathrm{O}_x$. The copper is a mixture of Cu (II) and $\mathrm{Cu}($ III) oxidation states. This mixture of oxidation states appears vital for high-temperature superconductivity to occur. A simple method for determining the average copper oxidation state has been reported [D. C. Harris, M. E. Hillis, and T. A. Hewston, J. Chem. Educ. $64,847(1987)]$. The described analysis takes place in two steps:
i. One superconductor sample is treated directly with $\mathrm{I}^{-}$:
$$
\begin{aligned}
& \mathrm{Cu}^{2+}(a q)+\mathrm{I}^{-}(a q) \longrightarrow \mathrm{CuI}(s)+\mathrm{I}_3^{-}(a q) \text { (Unbalanced) } \\
& \mathrm{Cu}^{3+}(a q)+\mathrm{I}^{-}(a q) \longrightarrow \mathrm{CuI}(s)+\mathrm{I}_3^{-}(a q) \text { (Unbalanced) }
\end{aligned}
$$
ii. A second superconductor sample is dissolved in acid, converting all copper to $\mathrm{Cu}(\mathrm{II})$. This solution is then treated with $\mathrm{I}^{-}$:
$$
\mathrm{Cu}^{2+}(a q)+\mathrm{I}^{-}(a q) \longrightarrow \mathrm{CuI}(s)+\mathrm{I}_3{ }^{-}(a q) \text { (Unbalanced) }
$$
In both steps the $\mathrm{I}_3^{-}$is determined by titrating with a standard sodium thiosulfate $\left(\mathrm{Na}_2 \mathrm{~S}_2 \mathrm{O}_3\right)$ solution:
$$
\mathrm{I}_3{ }^{-}(a q)+\mathrm{S}_2 \mathrm{O}_3{ }^{2-}(a q) \longrightarrow \mathrm{S}_4 \mathrm{O}_6{ }^{2-}(a q)+\mathrm{I}^{-}(a q)
$$
(Unbalanced)
a. Calculate the average copper oxidation states for materials with the formulas $\mathrm{YBa}_2 \mathrm{Cu}_3 \mathrm{O}_{6.5}$, $\mathrm{YBa}_2 \mathrm{Cu}_3 \mathrm{O}_7$, and $\mathrm{YBa}_2 \mathrm{Cu}_3 \mathrm{O}_8$. Interpret your results in terms of a mixture of $\mathrm{Cu}($ II) and Cu (III) ions, assuming that only $\mathrm{Y}^{3+}, \mathrm{Ba}^{2+}$, and $\mathrm{O}^{2-}$ are present in addition to the copper ions.
b. Balance the equations involved in the copper analysis.
c. A superconductor sample was analyzed by the above procedure. In step i, it took 37.77 mL of $0.1000 \mathrm{M} \mathrm{Na}_2 \mathrm{~S}_2 \mathrm{O}_3$ to react completely with the $\mathrm{I}_3{ }^{-}$ generated from a $562.5-\mathrm{mg}$ sample. In step ii, it took 22.57 mL of $0.1000 \mathrm{M} \mathrm{Na}_2 \mathrm{~S}_2 \mathrm{O}_3$ to react with the $\mathrm{I}_3{ }^{-}$generated by a $504.2-\mathrm{mg}$ sample. Determine the formula of this superconductor sample (that is, find the value of $x$ in $\mathrm{YBa}_2 \mathrm{Cu}_3 \mathrm{O}_x$ ). Calculate the average oxidation state of copper in this material.

Victor Salazar
Victor Salazar
Numerade Educator
19:25

Problem 133

You have two $500.0-\mathrm{mL}$ aqueous solutions. Solution A is a solution of a metal nitrate that is $8.246 \%$ nitrogen by mass. The ionic compound in solution B consists of potassium, chromium, and oxygen; chromium has an oxidation state of +6 , and there are 2 potassiums and 1 chromium in the formula. The masses of the solutes in each of the solutions are the same. When the solutions are added together, a blood-red precipitate forms. After the reaction has gone to completion, you dry the solid and find that it has a mass of 331.8 g .
a. Identify the ionic compounds in solution A and solution B.
b. Identify the blood-red precipitate.
c. Calculate the concentration (molarity) of all ions in the original solutions.
d. Calculate the concentration (molarity) of all ions in the final solution.

Natalie Almond
Natalie Almond
Numerade Educator