Chemistry

Kenneth W Whitten

Chapter 11

Reactions in Aqueous Solutions II: Calculations - all with Video Answers

Educators

Chapter Questions

Problem 1

Why can we describe molarity as a "method of convenience" for expressing concentrations of solutions?

Hannah Vigran

Hannah Vigran

Numerade Educator

Problem 2

Why is the molarity of a solution the same number whether we describe it in mol/L or in $\mathrm{mmol} / \mathrm{mL}$ ?

Hannah Vigran

Numerade Educator

Problem 3

Calculate the molarities of solutions that contain the following masses of solute in the indicated volumes: (a) $27.8 \mathrm{~g}$ of $\mathrm{H}_{3} \mathrm{AsO}_{4}$ in $400 . \mathrm{mL}$ of solution; (b) $6.33 \mathrm{~g}$ of $(\mathrm{COOH})_{2}$
in $500 . \mathrm{mL}$ of solution; (c) $6.33 \mathrm{~g}$ of $(\mathrm{COOH})_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}$ in
500. mL of solution.

Ronald Prasad

Numerade Educator

Problem 4

What is the molarity of a solution made by dissolving $44.4 \mathrm{~g}$ of magnesium sulfate in sufficient water to produce a total of $3.00 \mathrm{~L}=$

Ronald Prasad

Numerade Educator

Problem 5

There are $47.5 \mathrm{~g}$ of iron(II) nitrate present in $750 . \mathrm{mL}$ of solution. Calculate the molarity of that solution.

Ronald Prasad

Numerade Educator

Problem 6

Calculate the molarity of a solution that is $39.77 \% \mathrm{H}_{2} \mathrm{SO}_{4}$ by mass. The specific gravity of the solution is $1.305$.

Hannah Vigran

Numerade Educator

Problem 7

Calculate the molarity of a solution that is $19.0 \% \mathrm{HNO}_{3}$ by mass. The specific gravity of the solution is $1.11$.

Hannah Vigran

Numerade Educator

Problem 8

If $225 \mathrm{~mL}$ of $3.35 \mathrm{M}$ HCl solution is added to $426 \mathrm{~mL}$ of $1.77 M \mathrm{NaOH}$ solution, the resulting solution will be molar in $\mathrm{NaCl}$.

Ronald Prasad

Numerade Educator

Problem 9

What is the molarity of the salt solution produced when
500. mL of $3.00$ M HCl and 500. mL of $3.00 \mathrm{MLiOH}$ are mixed? Assume that the volumes are additive. Give the name and formula of the salt formed.

Ronald Prasad

Numerade Educator

Problem 10

Potassium iodide is sometimes used as a sodium chloride replacement for those people who cannot tolerate table salt. Calculate the molarity of potassium iodide solution produced when $55.5 \mathrm{~mL}$ of $8.99 M \mathrm{HI}$ and $35.4 \mathrm{~mL}$ of $14.1 \mathrm{M}$ KOH are mixed.

Ronald Prasad

Numerade Educator

Problem 11

What is the salt concentration produced if we mix $16.00 \mathrm{~mL}$ of $4.50 M \mathrm{HCl}$ with $9.00 \mathrm{~mL}$ of $4.00 \mathrm{M} \mathrm{Ba}(\mathrm{OH})_{2}^{2}$ Give the
name and formula of the salt formed.

Ronald Prasad

Numerade Educator

Problem 12

What is the concentration of barium iodide produced by mixing $7.50 \mathrm{~mL}$ of $0.135 \mathrm{M} \mathrm{Ba}(\mathrm{OH})_{2}$ with $19.4 \mathrm{~mL}$ of
$0.0650 M$ HI?

Ronald Prasad

Numerade Educator

Problem 13

What is the concentration of the ammonium chloride produced when $21.0 \mathrm{~mL}$ of $12.0 \mathrm{M} \mathrm{HCl}$ and $17.5 \mathrm{~mL}$ of $8.00 \mathrm{M} \mathrm{NH}_{3}$ are mixed?

Ronald Prasad

Numerade Educator

Problem 14

If 250. $\mathrm{mL}$ of $5.52 \mathrm{M} \mathrm{H}_{3} \mathrm{PO}_{4}$ solution is added to $775 \mathrm{~mL}$ of $5.52 \mathrm{M} \mathrm{NaOH}$ solution, the resulting solution will be molar in $\mathrm{Na}_{3} \mathrm{PO}_{4}$ and molar in

Marietjie Lutz

Numerade Educator

Problem 15

If $150 . \mathrm{mL}$ of $0.200 \mathrm{M} \mathrm{HCl}$ solution is added to $200 . \mathrm{mL}$ of $0.0400 \mathrm{M} \mathrm{Ba}(\mathrm{OH})_{2}$ solution, the resulting solution will be molar in $\mathrm{BaCl}_{2}$ and molar in

Ronald Prasad

Numerade Educator

Problem 16

A vinegar solution is $5.11 \%$ acetic acid. Its density is $1.007 \mathrm{~g} / \mathrm{mL}$. What is its molarity?

Marietjie Lutz

Numerade Educator

Problem 17

A household ammonia solution is $5.03 \%$ ammonia. Its density is $0.979 \mathrm{~g} / \mathrm{mL}$. What is its molarity?

Marietjie Lutz

Numerade Educator

Problem 18

(a) What volumes of $3.25 \mathrm{M} \mathrm{NaOH}$ and $4.50 \mathrm{M} \mathrm{H}_{3} \mathrm{PO}_{4}$
solutions would be required to form $1.00 \mathrm{~mol}$ of $\mathrm{Na}_{3} \mathrm{PO}_{4}^{2}$
(b) What volumes of the solutions would be required to form $1.00 \mathrm{~mol}$ of $\mathrm{Na}_{2} \mathrm{HPO}_{4}^{2}$

Ronald Prasad

Numerade Educator

Problem 19

Define and illustrate the following terms clearly and concisely: (a) standard solution; (b) titration; (c) primary standard; (d) secondary standard.

Ronald Prasad

Numerade Educator

Problem 20

Describe the preparation of a standard solution of $\mathrm{NaOH}$, a compound that absorbs both $\mathrm{CO}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$ from the air.

Ronald Prasad

Numerade Educator

Problem 21

Distinguish between the net ionic equation and the formula mit eanation

Ronald Prasad

Numerade Educator

Problem 22

(a) What is potassium hydrogen phthalate, KHP? (b) What is its major use?

Marietjie Lutz

Numerade Educator

Problem 23

Why can sodium carbonate be used as a primary standard for solutions of acids?

Marietjie Lutz

Numerade Educator

Problem 24

What volume of $0.145 \mathrm{M}$ acetic acid solution would completely neutralize $21.58 \mathrm{~mL}$ of $0.105 \mathrm{M} \mathrm{Ba}(\mathrm{OH})_{2}$
solution?

Marietjie Lutz

Numerade Educator

Problem 25

What volume of $0.150 M$ potassium hydroxide solution would completely neutralize $28.2 \mathrm{~mL}$ of $0.100 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}$ solution?

Ronald Prasad

Numerade Educator

Problem 26

Calculate the molarity of a solution of $\mathrm{HNO}_{3}$ if $15.72 \mathrm{~mL}$ of the solution neutralizes $0.2040 \mathrm{~g}$ of $\mathrm{Na}_{2} \mathrm{CO}_{3}$.

Ronald Prasad

Numerade Educator

Problem 27

If $45.38 \mathrm{~mL}$ of a sulfuric acid solution reacts completely with $0.3545 \mathrm{~g}$ of $\mathrm{Na}_{2} \mathrm{CO}_{3}$, what is the molarity of the sulfuric acid solution?

Ronald Prasad

Numerade Educator

Problem 28

A solution of sodium hydroxide is standardized against potassium hydrogen phthalate. From the following data, calculate the molarity of the $\mathrm{NaOH}$ solution. $\begin{array}{ll}\text { mass of KHP } & 0.5536 \mathrm{~g} \\ \text { buret reading before titration } & 0.23 \mathrm{~mL} \\ \text { buret reading after titration } & 37.26 \mathrm{~mL}\end{array}$

Marietjie Lutz

Numerade Educator

Problem 29

Calculate the molarity of a KOH solution if $30.68 \mathrm{~mL}$ of the KOH solution reacted with $0.4178 \mathrm{~g}$ of potassium hydrogen phthalate, KHP.

Marietjie Lutz

Numerade Educator

Problem 30

Calcium carbonate tablets can be used as an antacid and a source of dietary calcium. A bottle of generic antacid tablets states that each tablet contains $900 . \mathrm{mg}$ calcium carbonate. What volume of $1.0 M \mathrm{HCl}$ could be neutralized by the calcium carbonate in one tablet?

Marietjie Lutz

Numerade Educator

Problem 31

What volume of $9.00 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}$ is required to react with $65.5 \mathrm{~mL}$ of $6.00 \mathrm{M} \mathrm{NaOH}$ to produce a $\mathrm{Na}_{2} \mathrm{SO}_{4}$ solution?
What volume of water must be added to the resulting solution to obtain a $1.25 \mathrm{M} \mathrm{Na}_{2} \mathrm{SO}_{4}$ solution?

Ronald Prasad

Numerade Educator

Problem 32

(a) What are the properties of an ideal primary standard? (b) What is the importance of each property?

Ronald Prasad

Numerade Educator

Problem 33

The secondary standard solution of $\mathrm{NaOH}$ of Exercise 28 was used to titrate a solution of unknown concentration of HCl. A $30.00-\mathrm{mL}$ sample of the $\mathrm{HCl}$ solution required $28.21 \mathrm{~mL}$ of the $\mathrm{NaOH}$ solution for complete neutralization. What is the molarity of the HCl solution?

Marietjie Lutz

Numerade Educator

Problem 34

An impure sample of (COOH) $_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}$ that had a mass of $1.00 \mathrm{~g}$ was dissolved in water and titrated with standard $\mathrm{NaOH}$ solution. The titration required $19.16 \mathrm{~mL}$ of $0.298$ $M \mathrm{NaOH}$ solution. Calculate the percent $(\mathrm{COOH})_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}$
in the sample. Assume that the sample contains no acidic impurities.

Ronald Prasad

Numerade Educator

Problem 35

A 25.0-mL sample of $0.0400 \mathrm{MCa}(\mathrm{OH})_{2}$ is added to $15.0 \mathrm{~mL}$ of $0.100 \mathrm{M} \mathrm{HNO}_{3} .$ (a) Is the resulting solution acidic or basic? (b) How many moles of excess acid or base are present? (c) How many additional $\mathrm{mL}$ of $0.0400 \mathrm{M}$ $\mathrm{Ca}(\mathrm{OH})_{2}$ or $0.100 \mathrm{M} \mathrm{HNO}_{3}$ would be required to com-
pletely neutralize the solution?

Ronald Prasad

Numerade Educator

Problem 36

An antacid tablet containing calcium carbonate as an active ingredient required $26.8 \mathrm{~mL}$ of $0.112 \mathrm{MHCl}$ for complete neutralization. What mass of $\mathrm{CaCO}_{3}$ did the mblet contain?

Ronald Prasad

Numerade Educator

Problem 37

Butyric acid, whose empirical formula is $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{O}$, is the acid responsible for the odor of rancid butter. The acid has one ionizable hydrogen per molecule. A $1.187-\mathrm{g}$ sample of butyric acid is neutralized by $26.28 \mathrm{~mL}$ of $0.5132 \mathrm{M} \mathrm{NaOH}$ solution. What are (a) the molecular weight and (b) the molecular formula of butyric acid?

Ronald Prasad

Numerade Educator

Problem 38

What is the molarity of a solution of sodium hydroxide, $\mathrm{NaOH}$, if $41.4 \mathrm{~mL}$ of this solution is required to react with $37.5 \mathrm{~mL}$ of $0.0342 \mathrm{M}$ nitric acid solution according to the following reaction?
$$
\mathrm{HNO}_{3}+\mathrm{NaOH} \longrightarrow \mathrm{NaNO}_{3}+\mathrm{H}_{2} \mathrm{O}(\ell)
$$

Marietjie Lutz

Numerade Educator

Problem 39

What is the molarity of a solution of sodium hydroxide, $\mathrm{NaOH}$, if $18.45 \mathrm{~mL}$ of this solution is required to react with $17.60 \mathrm{~mL}$ of $0.181 M$ hydrochloric acid solution acoording to the following reaction?
$$
\mathrm{HCl}+\mathrm{NaOH} \longrightarrow \mathrm{NaCl}+\mathrm{H}_{2} \mathrm{O}(\ell)
$$

Ronald Prasad

Numerade Educator

Problem 40

What is the molarity of a solution that contains $0.978 \mathrm{~g}$ of $\mathrm{H}_{3} \mathrm{PO}_{4}$ in $185 \mathrm{~mL}$ of solution? How many milliliters of this solution could be completely neutralized by $11.58 \mathrm{~mL}$ of $0.454 \mathrm{M} \mathrm{NaOH}^{2}$

Ronald Prasad

Numerade Educator

Problem 41

What is the molarity of a sulfuric acid solution that is $19.6 \%$ $\mathrm{H}_{2} \mathrm{SO}_{4}$ by mass? The density of the solution is $1.14 \mathrm{~g} / \mathrm{mL} .$ How many milliliters of this solution could be completely neutralized by $11.58 \mathrm{~mL}$ of $0.454 M \mathrm{NaOH}$ ?

Ronald Prasad

Numerade Educator

Problem 42

Calculate the molarity of a solution that contains $18.6 \mathrm{~g}$ of arsenic acid, $\mathrm{H}_{3} \mathrm{As} \mathrm{O}_{4}$, in enough water to make $475 \mathrm{~mL}$ of solution. How many milliliters of this solution could be completely neutralized by $11.58 \mathrm{~mL}$ of $0.454 \mathrm{M} \mathrm{NaOH}$ ?

Ronald Prasad

Numerade Educator

Problem 43

Calculate the molarity of an $\mathrm{H}_{2} \mathrm{SO}_{4}$ solution if $48.8 \mathrm{~mL}$ of the solution reacts with $0.489 \mathrm{~g}$ of $\mathrm{Na}_{2} \mathrm{CO}_{3}$.
$$
\mathrm{H}_{2} \mathrm{SO}_{4}+\mathrm{Na}_{2} \mathrm{CO}_{3} \longrightarrow \mathrm{Na}_{2} \mathrm{SO}_{4}+\mathrm{CO}_{2}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\ell)
$$

Ronald Prasad

Numerade Educator

Problem 44

Calculate the molarity of an $\mathrm{HCl}$ solution if $39.1 \mathrm{~mL}$ of the solution reacts with $0.483 \mathrm{~g}$ of $\mathrm{Na}_{2} \mathrm{CO}_{3}$.
$$
2 \mathrm{HCl}+\mathrm{Na}_{2} \mathrm{CO}_{3} \longrightarrow 2 \mathrm{NaCl}+\mathrm{CO}_{2}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\ell)
$$

Marietjie Lutz

Numerade Educator

Problem 45

To minimize the effect of buret reading errors, titrations performed using a $50-\mathrm{mL}$ buret are most accurate when titrant volumes are in the range of 35 to $45 \mathrm{~mL}$. Suggest a range of sample weights that would yield a 35 - to 45 -mL titration range for the standardization of solutions of the following approximate concentrations.
(a) $0.0533 \mathrm{M} \mathrm{NaOH}$
using potassium hydrogen phthalate $\left(\mathrm{C}_{8} \mathrm{H}_{5} \mathrm{KO}_{4}\right)$, a monoprotic acid. (b) $0.0895 M$ KOH using primary standard benzoic acid $\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH}\right)$, a monoprotic acid.

Ronald Prasad

Numerade Educator

Problem 46

Magnesium hydroxide, $\mathrm{Mg}(\mathrm{OH})_{2}$, is commonly used as the active ingredient in antacid tablets. A student analyzed an antacid tablet for mass percent $\mathrm{Mg}(\mathrm{OH})_{2}$ by dissolving a tablet weighing $1.462 \mathrm{~g}$ in $25.00 \mathrm{~mL}$ of $0.953 \mathrm{M} \mathrm{HCl}$, and neutralizing the unreacted HCl. That neutralization required $12.29 \mathrm{~mL}$ of $0.602 \mathrm{M} \mathrm{NaOH}$. Calculate the mass percent of $\mathrm{Mg}(\mathrm{OH})_{2}$ in the antacid tablet.

Ronald Prasad

Numerade Educator

Problem 47

Vinegar is an aqueous solution of acetic acid, $\mathrm{CH}_{3} \mathrm{COOH}$. Suppose you titrate a $25.00-\mathrm{mL}$ sample of vinegar with $17.62 \mathrm{~mL}$ of a standardized $0.1045 \mathrm{~N}$ solution of $\mathrm{NaOH}$.
(a) What is the molarity of acetic acid in this vinegar?
(b) What is the mass of acetic acid contained in $1.000 \mathrm{~L}$ of vinegar?

Ronald Prasad

Numerade Educator

Problem 48

(a) Iron reacts with hydrochloric acid to form aqueous iron(II) chloride and gaseous hydrogen. (b) Chromium reacts with sulfuric acid to form aqueous chromium(III) sulfate and gaseous hydrogen. (c) Tin reacts with concentrated nitric acid to form tin(IV) oxide, nitrogen dioxide, and water.

Ronald Prasad

Numerade Educator

Problem 49

(a) Carbon reacts with hot concentrated nitric acid to form carbon dioxide, nitrogen dioxide, and water. (b) Sodium reacts with water to form aqueous sodium hydroxide and gaseous hydrogen. (c) Zinc reacts with sodium hydroxide solution to form aqueous sodium tetrahydroxozincate and gaseous hydrogen. (The tetrahydroxozincate ion is $\left.\left[\mathrm{Zn}(\mathrm{OH})_{4}\right]^{2-} .\right)$

Ronald Prasad

Numerade Educator

Problem 50

Copper is a widely used metal. Before it is welded (brazed), copper is cleaned by dipping it into nitric acid. HNO $_{3}$ oxidizes $C u$ to $\mathrm{Cu}^{2+}$ ions and is reduced to $\mathrm{NO}$. The other product is $\mathrm{H}_{2} \mathrm{O} .$ Write the balanced net ionic and formula unit equations for the reaction. Excess $\mathrm{HNO}_{3}$, is present.

Ronald Prasad

Numerade Educator

Problem 51

Balance the following equations. For each equation tell what is oxidized, what is reduced, what the oxidizing agent is, and what the reducing agent is. (a) $\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{~s}) \stackrel{\text { heat }}{\longrightarrow} \mathrm{CuO}(\mathrm{s})+\mathrm{NO}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g})$
(b) $\mathrm{Hg}_{2} \mathrm{Cl}_{2}(\mathrm{~s})+\mathrm{NH}_{3}(\mathrm{aq}) \stackrel{\longrightarrow}{\mathrm{Hg}(\ell)}+\mathrm{HgNH}_{2} \mathrm{Cl}(\mathrm{s})+\mathrm{NH}_{4}+(\mathrm{aq})+\mathrm{Cl}^{-}(\mathrm{aq})$
(c) $\mathrm{Ba}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\ell) \longrightarrow \mathrm{Ba}(\mathrm{OH})_{2}(\mathrm{aq})+\mathrm{H}_{2}(\mathrm{~g})$

Lottie Adams

Numerade Educator

Problem 52

Balance the following equations. For each equation tell what is oxidized, what is reduced, what the oxidizing agent is, and what the reducing agent is.
(a) $\mathrm{MnO}_{4}^{-}(\mathrm{aq})+\mathrm{H}^{+}(\mathrm{aq})+\mathrm{Br}^{-}(\mathrm{aq}) \longrightarrow$
$\mathrm{Mn}^{2+}(\mathrm{aq})+\mathrm{Br}_{2}(\ell)+\mathrm{H}_{2} \mathrm{O}(\ell)$
(b) $\mathrm{Cr}_{2} \mathrm{O}_{7}{ }^{2-}(\mathrm{aq})+\mathrm{H}^{+}(\mathrm{aq})+\mathrm{I}^{-}(\mathrm{aq}) \longrightarrow$
$\mathrm{Cr}^{3+}(\mathrm{aq})+\mathrm{I}_{2}(\mathrm{~s})+\mathrm{H}_{2} \mathrm{O}(\ell)$
(c) $\mathrm{MnO}_{4}^{-}(\mathrm{aq})+\mathrm{SO}_{3}{ }^{2-}(\mathrm{aq})+\mathrm{H}^{+}(\mathrm{aq}) \longrightarrow$
$\mathrm{Mn}^{2+}(\mathrm{aq})+\mathrm{SO}_{4}{ }^{2-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)$
(d) $\mathrm{Cr}_{2} \mathrm{O}_{7}{ }^{2-}(\mathrm{aq})+\mathrm{Fe}^{2+}(\mathrm{aq})+\mathrm{H}^{+}(\mathrm{aq}) \longrightarrow$
$\mathrm{Cr}^{3+}(\mathrm{aq})+\mathrm{Fe}^{3+}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)$

Nicole Mabante

Numerade Educator

Problem 53

Balance the following ionic equations. For each equation tell what is oxidized, what is reduced, what the oxidizing agent is, and what the reducing agent is.
(a) $\mathrm{C}_{2} \mathrm{H}_{4}(\mathrm{~g})+\mathrm{MnO}_{4}^{-}(\mathrm{aq})+\mathrm{H}^{+}(\mathrm{aq}) \longrightarrow$
$\mathrm{CO}_{2}(\mathrm{~g})+\mathrm{Mn}^{2+}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)$
(b) $\mathrm{H}_{2} \mathrm{~S}(\mathrm{aq})+\mathrm{H}^{+}(\mathrm{aq})+\mathrm{Cr}_{2} \mathrm{O}_{7}{ }^{2-}(\mathrm{aq}) \stackrel{\mathrm{C}^{3+}}{\longrightarrow}+\mathrm{S}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\ell)$
(c) $\mathrm{ClO}_{3}^{-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{I}_{2}(\mathrm{~s}) \longrightarrow$
$\mathrm{IO}_{3}^{-}(\mathrm{aq})+\mathrm{Cl}^{-}(\mathrm{aq})+\mathrm{H}^{+}(\mathrm{aq})$
(d) $\mathrm{Cu}(\mathrm{s})+\mathrm{H}^{+}(\mathrm{aq})+\mathrm{SO}_{4}{ }^{2-}(\mathrm{aq}) \stackrel{\mathrm{Cu}^{2+}(\mathrm{aq})}+\mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{SO}_{2}(\mathrm{~g})$

Aadit Sharma

Numerade Educator

Problem 54

Dräno drain cleaner is solid sodium hydroxide that contains some aluminum chips. When Drano is added to water, the $\mathrm{NaOH}$ dissolves rapidly with the evolution of a lot of heat. The $\mathrm{Al}$ reduces $\mathrm{H}_{2} \mathrm{O}$ in the basic solution to produce $\left[\mathrm{Al}(\mathrm{OH})_{4}\right]^{-}$ ions and $\mathrm{H}_{2}$ gas, which gives the bubbling action. Write the balanced net ionic and formula unit equations for this reaction.

Ronald Prasad

Numerade Educator

Problem 55

Balance the following ionic equations. For cach equation tell what is oxidized, what is reduced, what the oxidizing agent is, and what the reducing agent is.
(a) $\mathrm{Cr}(\mathrm{OH})_{4}^{-}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{aq}) \longrightarrow$
$\mathrm{CrO}_{4}^{2-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)$
(b) $\mathrm{MnO}_{2}(\mathrm{~s})+\mathrm{H}^{+}(\mathrm{aq})+\mathrm{NO}_{2}^{-}(\mathrm{aq}) \longrightarrow$
$\mathrm{NO}_{3}^{-}(\mathrm{aq})+\mathrm{Mn}^{2+}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)$
(c) $\mathrm{Sn}(\mathrm{OH})_{3}^{-}(\mathrm{aq})+\mathrm{Bi}(\mathrm{OH})_{3}(\mathrm{~s})+\mathrm{OH}(\mathrm{aq}) \longrightarrow$
$\mathrm{Sn}(\mathrm{OH})_{6}{ }^{2-}(\mathrm{aq})+\mathrm{Bi}(\mathrm{s})$
(d) $\mathrm{CrO}_{4}{ }^{2-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{HSnO}_{2}^{-}(\mathrm{aq}) \longrightarrow$
$\mathrm{CrO}_{7}^{-}(\mathrm{ag})+\mathrm{OH}^{-}(\mathrm{aq})+\mathrm{HSnO}_{4}^{-}(\mathrm{aq})$

Aadit Sharma

Numerade Educator

Problem 56

Balance the following ionic equations for reactions in acidic solution. $\mathrm{H}^{+}$ or $\mathrm{H}_{2} \mathrm{O}$ (but not $\mathrm{OH}^{-}$ ) may be added as necessary.
(a) $\mathrm{Fe}^{2+}(\mathrm{aq})+\mathrm{MnO}_{4}^{-}(\mathrm{aq}) \longrightarrow \mathrm{Fe}^{3+}(\mathrm{aq})+\mathrm{Mn}^{2+}(\mathrm{aq})$
(b) $\mathrm{Br}_{2}(\ell)+\mathrm{SO}_{2}(\mathrm{~g}) \longrightarrow \mathrm{Br}^{-}(\mathrm{aq})+\mathrm{SO}_{4}^{2-}(\mathrm{aq})$
(c) $\mathrm{Cu}(\mathrm{s})+\mathrm{NO}_{3}^{-}(\mathrm{aq}) \longrightarrow \mathrm{Cu}^{2+}(\mathrm{aq})+\mathrm{NO}_{2}(\mathrm{~g})$
(d) $\mathrm{PbO}_{2}(\mathrm{~s})+\mathrm{Cl}^{-}(\mathrm{aq}) \longrightarrow \mathrm{PbCl}_{2}(\mathrm{~s})+\mathrm{Cl}_{2}(\mathrm{~g})$
(c) $\mathrm{Zn}(\mathrm{s})+\mathrm{NO}_{3}^{-}(\mathrm{aq}) \longrightarrow \mathrm{Zn}^{2+}(\mathrm{aq})+\mathrm{N}_{2}(\mathrm{~g})$

LJ

Lena Jake

Numerade Educator

Problem 57

Balance the following ionic equations for reactions in acidic solution. $\mathrm{H}^{+}$ or $\mathrm{H}_{2} \mathrm{O}$ (but $\left.\mathrm{not} \mathrm{OH}^{-}\right)$ may be added as necessary.
(a) $\mathrm{P}_{4}(\mathrm{~s})+\mathrm{NO}_{3}^{-}(\mathrm{aq}) \longrightarrow \mathrm{H}_{3} \mathrm{PO}_{4}(\mathrm{aq})+\mathrm{NO}(\mathrm{g})$
(b) $\mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{aq})+\mathrm{MnO}_{4}^{-}(\mathrm{aq}) \longrightarrow \mathrm{Mn}^{2+}(\mathrm{aq})+\mathrm{O}_{2}(\mathrm{~g})$
(c) $\mathrm{HgS}(\mathrm{s})+\mathrm{Cl}^{-}(\mathrm{aq})+\mathrm{NO}_{3}^{-}(\mathrm{aq}) \longrightarrow$
$\mathrm{HgCl}_{4}^{2-}(\mathrm{aq})+\mathrm{NO}_{2}(\mathrm{~g})+\mathrm{S}(\mathrm{s})$
(d) $\mathrm{HBrO}(\mathrm{aq}) \longrightarrow \mathrm{Br}^{-}(\mathrm{aq})+\mathrm{O}_{2}(\mathrm{~g})$

Ronald Prasad

Numerade Educator

Problem 58

Write the balanced net ionic equations for the reactions given. Then, using the reactants shown in parentheses, convert each balanced net ionic equation to a balanced formula unit equation.
(a) $\mathrm{MnO}_{4}^{-}+\mathrm{C}_{2} \mathrm{O}_{4}{ }^{2-}+\mathrm{H}^{+} \longrightarrow$
$\mathrm{Mn}^{2+}+\mathrm{CO}_{2}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\ell)$
$\left(\mathrm{KMnO}_{4}, \mathrm{HCl}\right.$, and $\left.\mathrm{K}_{2} \mathrm{C}_{2} \mathrm{O}_{4}\right)$
(b) $\mathrm{Zn}+\mathrm{NO}_{3}^{-}+\mathrm{H}^{+} \longrightarrow \mathrm{Zn}^{2+}+\mathrm{NH}_{4}^{+}+\mathrm{H}_{2} \mathrm{O}(\ell)$
$\left(\mathrm{Zn}(\mathrm{s})\right.$ and $\left.\mathrm{HNO}_{3}\right)$

Ronald Prasad

Numerade Educator

Problem 59

Write the balanced net ionic equations for the reactions given. Then, using the reactants shown in parentheses, conwert each balanced net ionic equation to a balanced formula unit equation.
(a) $\mathrm{I}_{2}+\mathrm{S}_{2} \mathrm{O}_{3}^{2-} \longrightarrow \mathrm{I}^{2}+\mathrm{S}_{4} \mathrm{O}_{6}^{2-} \quad\left(\mathrm{I}_{2}\right.$ and $\left.\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}\right)$
(b) $\mathrm{IO}_{3}^{-}+\mathrm{N}_{2} \mathrm{H}_{4}+\mathrm{Cl}^{-}+\mathrm{H}^{+} \longrightarrow$
$\mathrm{N}_{2}(\mathrm{~g})+\mathrm{ICl}_{2}^{-}+\mathrm{H}_{2} \mathrm{O}(\ell)$
$\left(\mathrm{NaIO}_{3}+\mathrm{N}_{2} \mathrm{H}_{4}\right.$, and $\left.\mathrm{HCl}\right)$

Ronald Prasad

Numerade Educator

Problem 60

Write the balanced net ionic equations for the reactions given. Then, using the reactants shown in parentheses, convert each balanced net ionic equation to a balanced formula unit equation.
(a) $\mathrm{Zn}(\mathrm{s})+\mathrm{Cu}^{2+} \longrightarrow \mathrm{Cu}(\mathrm{s})+\mathrm{Zn}^{2+} \quad\left(\mathrm{Zn}\right.$ and $\left.\mathrm{CuSO}_{4}\right)$
(b) $\mathrm{Cr}(\mathrm{s})+\mathrm{H}^{+} \longrightarrow \mathrm{Cr}^{3+}+\mathrm{H}_{2}(\mathrm{~g})$
$\left(\mathrm{Cr}\right.$ and $\left.\mathrm{H}_{2} \mathrm{SO}_{4}\right)$

Ronald Prasad

Numerade Educator

Problem 61

Write the balanced net ionic equations for the reactions given. Then, using the reactants shown in parentheses, convert each balanced net ionic equation to a balanced formula unit cquation.
(a) $\mathrm{Cl}_{2}+\mathrm{OH}^{-} \longrightarrow \mathrm{ClO}_{3}^{-}+\mathrm{Cl}^{-}+\mathrm{H}_{2} \mathrm{O}(\ell)$
$\left(\mathrm{Cl}_{2}\right.$ and hot $\mathrm{NaOH}$ )
(b) $\mathrm{Pb}(\mathrm{s})+\mathrm{H}^{+}+\mathrm{Br}^{-} \longrightarrow \mathrm{PbBr}_{2}(\mathrm{~s})+\mathrm{H}_{2}(\mathrm{~g})$
$(\mathrm{Pb}(\mathrm{s})$ and $\mathrm{HBr})$

Ronald Prasad

Numerade Educator

Problem 62

What volume of $0.213 \mathrm{M} \mathrm{KMnO}_{4}$ would be required to oxidize $25.0 \mathrm{~mL}$ of $0.150 \mathrm{M} \mathrm{FeSO}_{4}$ in acidic solution?

Ronald Prasad

Numerade Educator

Problem 63

What volume of $0.213 \mathrm{MK}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ would be required to oxidize $70.0 \mathrm{~mL}$ of $0.150 \mathrm{M} \mathrm{Na}_{2} \mathrm{SO}_{3}$ in acidic solution? The products include $\mathrm{Cr}^{3+}$ and $\mathrm{SO}_{4}{ }^{2-}$ ions.

Ronald Prasad

Numerade Educator

Problem 64

What volume of $0.190 \mathrm{MKMnO}_{4}$ would be required to oxidize $27.0 \mathrm{~mL}$ of $0.150 \mathrm{M} \mathrm{KI}$ in acidic solution? Products include $\mathrm{Mn}^{2+}$ and $\mathrm{I}_{2}$.

Ronald Prasad

Numerade Educator

Problem 65

What volume of $0.190 \mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ would be required to oxidize $27.0 \mathrm{~mL}$ of $0.250 \mathrm{M} \mathrm{KI}$ in acidic solution? Products include $\mathrm{Cr}^{3+}$ and $\mathrm{I}_{2}$.

Ronald Prasad

Numerade Educator

Problem 66

(a) $\mathrm{A}$ solution of sodium thiosulfate, $\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}$, is $0.1442 \mathrm{M}$. $37.00 \mathrm{~mL}$ of this solution reacts with $28.85 \mathrm{~mL}$ of $\mathrm{I}_{2}$ solution. Calculate the molarity of the $\mathrm{I}_{2}$ solution.
$$
2 \mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}+\mathrm{I}_{2} \longrightarrow \mathrm{Na}_{2} \mathrm{~S}_{4} \mathrm{O}_{6}+2 \mathrm{NaI}
$$
(b) $35.32 \mathrm{~mL}$ of the $\mathrm{I}_{2}$ solution is required to titrate a sample containing $\mathrm{As}_{2} \mathrm{O}_{3} .$ Calculate the mass of $\mathrm{As}_{2} \mathrm{O}$, $(197.8 \mathrm{~g} / \mathrm{mol})$ in the sample.
$$
\mathrm{As}_{2} \mathrm{O}_{3}+5 \mathrm{H}_{2} \mathrm{O}(\ell)+2 \mathrm{I}_{2} \longrightarrow 2 \mathrm{H}_{3} \mathrm{~A}_{5} \mathrm{O}_{4}+4 \mathrm{HI}
$$

Ronald Prasad

Numerade Educator

Problem 67

Copper(II) ions, $\mathrm{Cu}^{2+}$, can be determined by the net reaction
$$
2 \mathrm{Cu}^{2+}+2 \mathrm{I}^{-}+2 \mathrm{~S}_{2} \mathrm{O}_{3}^{2-} \longrightarrow 2 \mathrm{CuI}(\mathrm{s})+\mathrm{S}_{4} \mathrm{O}_{6}^{2-}
$$
A $4.115-\mathrm{g}$ sample containing $\mathrm{CuSO}_{4}$ and excess $\mathrm{KI}$ is titrated with $32.55 \mathrm{~mL}$ of $0.2214 M$ solution of $\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}$. What is the percent $\mathrm{CuSO}_{4}(159.6 \mathrm{~g} / \mathrm{mol})$ in the sample?

Ronald Prasad

Numerade Educator

Problem 68

What volume of $5.0 M$ nitrate ion solution would be required to react with $35 . \mathrm{mL}$ of $0.75 \mathrm{M}$ sulfide ion solution? (Hint: The equation is not balanced.)
$$
\mathrm{NO}_{3}^{-}+\mathrm{S}^{2-} \longrightarrow \mathrm{NO}+\mathrm{S}(\mathrm{s})
$$

Ronald Prasad

Numerade Educator

Problem 69

The iron in a $6.675-g$ sample containing some $\mathrm{Fe}_{2} \mathrm{O}_{3}$ is reduced to $\mathrm{Fe}^{2+}$. The $\mathrm{Fe}^{2+}$ is titrated with $14.42 \mathrm{~mL}$ of $0.1467 \mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ in an acid solution.
$6 \mathrm{Fe}^{2+}+\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+14 \mathrm{H}^{+} \longrightarrow$
$6 \mathrm{Fe}^{3+}+2 \mathrm{Cr}^{3+}+7 \mathrm{H}_{2} \mathrm{O}(\ell)$
Find (a) the mass of Fe and (b) the percentage of Fe in the samplc.

Ronald Prasad

Numerade Educator

Problem 70

Calculate the molarity of a solution that contains $14.6 \mathrm{~g}$ of $\mathrm{KMnO}_{4}$ in $750 . \mathrm{mL}$ of solution to be used in the reaction that produces $\mathrm{MnO}_{4}^{2-}$ ions as the reduction product.

Ronald Prasad

Numerade Educator

Problem 71

A $0.855$ -g sample of an ore of iron is dissolved in acid and converted to $\mathrm{Fe}(\mathrm{II})$. The sample is oxidized by $36.50 \mathrm{~mL}$ of $0.161 M$ ceric sulfate, $\mathrm{Ce}\left(\mathrm{SO}_{4}\right)_{2}$, solution; the cerium(IV) ion, $\mathrm{Ce}^{4+}$, is reduced to $\mathrm{Ce}^{3+}$ ion. (a) Write a balanced equation for the reaction. (b) What is the percent iron in the ore?

Ronald Prasad

Numerade Educator

Problem 72

Calculate the molarity of a hydrochloric acid solution if $32.75 \mathrm{~mL}$ fully reacts with $0.4811 \mathrm{~g}$ of sodium carbonate.

Ronald Prasad

Numerade Educator

Problem 73

Calculate the molarity of a sulfuric acid solution if $38.75 \mathrm{~mL}$ of it reacts completely with $0.3911 \mathrm{~g}$ of sodium carbonate.

Marietjie Lutz

Numerade Educator

Problem 74

Find the number of $\mathrm{mmol}$ of $\mathrm{HCl}$ that reacts with $25.5 \mathrm{~mL}$ of $0.298 \mathrm{M} \mathrm{NaOH}$. What volume of $0.606 \mathrm{M} \mathrm{HCl}$ is needed to furnish this amount of $\mathrm{HCl}$ ?

Ronald Prasad

Numerade Educator

Problem 75

What is the composition of the final solution when $25.5 \mathrm{~mL}$ of $0.298 \mathrm{M} \mathrm{NaOH}$ and $25.5 \mathrm{~mL}$ of $0.410 \mathrm{M}$ HCl solutions are mixed?

Ronald Prasad

Numerade Educator

Problem 76

What volume of $0.1153 M \mathrm{HCl}$ is needed to completely neutralize $1.79 \mathrm{~g}$ of $\mathrm{Ca}(\mathrm{OH})_{2} ?$

Ronald Prasad

Numerade Educator

Problem 77

What mass of $\mathrm{NaOH}$ is needed to neutralize $34.50 \mathrm{~mL}$ of $0.1036 M \mathrm{HCl}^{2}$ If the $\mathrm{NaOH}$ is available as a $0.1533 \mathrm{M}$
aqueous solution, what volume will be required?

Ronald Prasad

Numerade Educator

Problem 78

What volume of $0.296 M \mathrm{H}_{2} \mathrm{SO}_{4}$ solution would be required to neutralize completely $34.4 \mathrm{~mL}$ of $0.322 \mathrm{M} \mathrm{KOH}$ solution?

Ronald Prasad

Numerade Educator

Problem 79

What volume of $0.344 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}$ solution would be required to neutralize completely $34.4 \mathrm{~mL}$ of $0.302 \mathrm{M} \mathrm{KOH}$ solution?

Ronald Prasad

Numerade Educator

Problem 80

What volume of $0.1945 M$ sodium hydroxide would be required to neutralize completely $34.38 \mathrm{~mL}$ of $0.1023$ $M \mathrm{H}_{2} \mathrm{SO}_{4}$ solution?

Ronald Prasad

Numerade Educator

Problem 81

Benzoic acid, $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH}$, is sometimes used as a primary standard for the standardization of solutions of bases. A $1.862-\mathrm{g}$ sample of this acid is neutralized by $35.00 \mathrm{~mL}$ of $\mathrm{NaOH}$ snlution. What is the molarity of the hase solution?
$\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH}(\mathrm{s})+\mathrm{NaOH}(\mathrm{aq}) \longrightarrow$

Ronald Prasad

Numerade Educator

Problem 82

Find the volume of $0.245 M$ HI solution required to titrate
(a) $25.0 \mathrm{~mL}$ of $0.100 \mathrm{M} \mathrm{NaOH}$
(b) $0.503 \mathrm{~g}$ of $\mathrm{AgNO}_{3}\left(\mathrm{Ag}^{+}+\mathrm{I} \longrightarrow \mathrm{AgI}(\mathrm{s})\right)$
(c) $0.621 \mathrm{~g} \mathrm{CuSO}_{4}\left(2 \mathrm{Cu}^{2+}+4 \mathrm{I}^{-} \longrightarrow 2 \mathrm{CuI}(\mathrm{s})+\mathrm{I}_{2}(\mathrm{~s})\right)$

Ronald Prasad

Numerade Educator

Problem 83

Describe how you could prepare $1.00 \mathrm{~L}$ of $1.00 \times 10^{-6} M$ $\mathrm{NaCl}$ solution by using a balance that can measure masses only to the nearest $0.01 \mathrm{~g}$.

Ronald Prasad

Numerade Educator

Problem 84

Ascorbic acid (vitamin C), along with many other reputed properties, acts as an antioxidant. The following equation illustrates its antioxidant properties.
$$
\mathrm{H}_{2} \mathrm{C}_{6} \mathrm{H}_{6} \mathrm{O}_{6} \longrightarrow \mathrm{C}_{6} \mathrm{H}_{6} \mathrm{O}_{6}+\mathrm{H}_{2}(\mathrm{~g})
$$
What is an antioxidant? Assign oxidation numbers. Is vitamin C oxidized or reduced in this reaction?

Ronald Prasad

Numerade Educator

Problem 85

For the formation of $1.00 \mathrm{~mol}$ of water, which reaction uses the most nitric acid?
(a) $3 \mathrm{Cu}(\mathrm{s})+8 \mathrm{HNO}_{3}(\mathrm{aq}) \longrightarrow$
$3 \mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+2 \mathrm{NO}(\mathrm{g})+4 \mathrm{H}_{2} \mathrm{O}(\ell)$
(b) $\mathrm{Al}_{2} \mathrm{O}_{3}(\mathrm{~s})+6 \mathrm{HNO}_{3}(\mathrm{aq}) \longrightarrow$
(c) $4 \mathrm{Zn}(\mathrm{s})+10 \mathrm{HNO}_{3}(\mathrm{aq}) \longrightarrow$
$4 \mathrm{Zn}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+\mathrm{NH}_{4} \mathrm{NO}_{3}(\mathrm{aq})+3 \mathrm{H}_{2} \mathrm{O}(\ell)$

Ronald Prasad

Numerade Educator

Problem 86

Limonite is an ore of iron that contains $2 \mathrm{Fe}_{2} \mathrm{O}_{3} \cdot 3 \mathrm{H}_{2} \mathrm{O}$. A $0.5166-\mathrm{g}$ sample of limonite is dissolved in acid and treated so that all the iron is converted to ferrous ions, $\mathrm{Fe}^{2+}$. This sample requires $42.96 \mathrm{~mL}$ of $0.02130 \mathrm{M}$ sodium dichromate solution, $\mathrm{Na}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$, for titration. $\mathrm{Fe}^{2+}$ is oxidized to $\mathrm{Fe}^{3+}$, and $\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}$ is reduced to $\mathrm{Cr}^{3+}$. What is the percent iron in the limonite? If your answer had been over $100 \%$ limonite, what conclusion could you make, presuming that the analytical data are correct?

Ronald Prasad

Numerade Educator

Problem 87

One of the troublesome products of a water treatment plant in some areas of the country is $\mathrm{Mg}(\mathrm{OH})_{2}$, a gelatinous precipitate formed during water softening. A suggestion was made that instead of shoveling the precipitate out of the pool during cleaning, the $\mathrm{Mg}(\mathrm{OH})_{2}$ could be neutralized with hydrochloric acid to produce a soluble compound, $\mathrm{MgCl}_{2}$. Then the pool could be flushed out with fresh water. Calculate the volume of $12.0 M$ HCl necessary to neutralize $3750 \mathrm{~L}$ of solution containing $1.50 \mathrm{~g}$ of $\mathrm{Mg}(\mathrm{OH})_{2}$ per liter.

Marietjie Lutz

Numerade Educator

Problem 88

Silver nitrate and calcium chloride solutions produce a heavy, white precipitate when mixed. Chemical analysis indicates that the precipitate is silver chloride. What mass of silver chloride would be produced if $95 \mathrm{~mL}$ of $6.0 \mathrm{M}$ silver nitrate is mixed with $40 \mathrm{~mL}$ of $6.0 M$ calcium chloride?

Marietjie Lutz

Numerade Educator

Problem 89

A $0.500-g$ sample of a crystalline monoprotic acid was dissolved in sufficient water to produce $100 . \mathrm{mL}$ of solution. Neutralization of the resulting solution required $75.0 \mathrm{~mL}$ of $0.150 \mathrm{MNaOH}$. How many moles of the acid were present in the initial acid solution?

Ronald Prasad

Numerade Educator

Problem 90

The typical concentration of hydrochloric acid in stomach acid (digestive juice) is about $8.0 \times 10^{-2} M$. One experiences "acid stomach" when the stomach contents reach about $1.0 \times 10^{-1} \mathrm{M} \mathrm{HCl}$. One antacid tablet contains $334 \mathrm{mg}$ of active ingredient, $\mathrm{NaAl}(\mathrm{OH})_{2} \mathrm{CO}_{3} .$ Assume that you have acid stomach and that your stomach contains
800. $\mathrm{mL}$ of $1.0 \times 10^{-1} \mathrm{M}$ HCl. Calculate the number of mmol of $\mathrm{HCl}$ in the stomach and the number of $\mathrm{mmol}$ of $\mathrm{HCl}$ that the tablet $\mathrm{cm}$ neutralize. Which is greater? (The neutralization reaction produces $\mathrm{NaCl}, \mathrm{AlCl}_{3}, \mathrm{CO}_{2}$, and $\mathrm{H}_{2} \mathrm{O} .$ )

Ronald Prasad

Numerade Educator

Problem 91

Write a Lewis formula for the anion $\mathrm{SiF}_{6}{ }^{2-}$ that would be produced from the weak acid $\mathrm{H}_{2} \mathrm{SiF}_{6}$. Use the VSEPR theory to predict the shape of $\mathrm{SiF}_{6}{ }^{2-}$.

Ronald Prasad

Numerade Educator

Problem 92

The etching of glass by hydrofluoric acid may be represented by the simplified reaction of silica with HF.
$$
\mathrm{SiO}_{2}(\mathrm{~s})+\mathrm{HF}(\mathrm{aq}) \longrightarrow \mathrm{H}_{2} \mathrm{SiF}_{6}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)
$$
This is an acid-base reaction in which a weak acid is used to produce an even weaker acid. Is it also an oxidationreduction reaction? Balance the equation.

Ronald Prasad

Numerade Educator

Problem 93

Oxalic acid, a poisonous compound, is found in certain vegetables such as spinach and rhubarb, but in concentrations well below toxic limits. The manufacturers of a spinach juice concentration routinely test their product using an oxalic acid analysis to avoid any problems from an uncxpectedly high concentration of this chemical. A titration with potassium permanganate is used for the oxalic acid assay, according to the following net equation. $5 \mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}+2 \mathrm{MnO}_{4}^{-}+6 \mathrm{H}^{+} \longrightarrow$
$10 \mathrm{CO}_{2}+2 \mathrm{Mn}^{2+}+8 \mathrm{H}_{2} \mathrm{O}(\ell)$
Calculate the molarity of an oxalic acid solution requiring $23.2 \mathrm{~mL}$ of $0.127 \mathrm{M}$ permanganate for a $25.0 \mathrm{~mL}$ portion of the solution.

Ronald Prasad

Numerade Educator

Problem 94

Consider the two electrostatic charge potential plots for potassium hydrogen phthalate (KHP) shown below. Which is more stable (has a lower energy) and why?

Ronald Prasad

Numerade Educator

Problem 95

Use an Internet search engine to locate information on stomach acid.
(a) What is the molarity of the acid in a normal stomach? (b) What acid(s) is (are) present in the stomach?

Ronald Prasad

Numerade Educator

Problem 96

Use an Internet search engine to locate information on each of the following terms. Define three of the four following terms as they relate to titrations: (a) aliquot, (b) analyte, (c) titrant, and (d) scout titration (not associated with Boy Scouts).

Ronald Prasad

Numerade Educator

Problem 97

Use an Internet search engine to locate information on each of the following concepts. Define three of the following four as they relate to titrations: (a) back titration, (b) concave meniscus, (c) Karl Fischer titration, and (d) parallax error.

Ronald Prasad

Numerade Educator

Problem 98

Use an Internet search engine to locate information on "pool chemistry." Define total alkalinity. Why should a pool owner be concerned about total alkalinity?

Ronald Prasad

Numerade Educator