Chemistry

John E. Mcmurry, Robert C. Fay, Jordan Fantini

Chapter 4

Reactions in Aqueous Solution - all with Video Answers

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Chapter Questions

Problem 1

Classify each of the following processes as a precipitation, acid–base neutralization, or redox reaction:
(a) $\mathrm{AgNO}_{3}(a q)+\mathrm{KCl}(a q) \longrightarrow \mathrm{AgCl}(s)+\mathrm{KNO}_{3}(a q)$
(b) $\mathrm{Cl}_{2}(g)+2 \mathrm{NaBr}(a q) \longrightarrow \mathrm{Br}_{2}(a q)+2 \mathrm{NaCl}(a q)$
(c) $\mathrm{Ca}(\mathrm{OH})_{2}(a q)+2 \mathrm{HNO}_{3}(a q) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(l)+\mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}(a q)$

AA

A Adly

Numerade Educator

Problem 2

What is the molar concentration of $\mathrm{Br}^{-}$ ions in a 0.225 $\mathrm{M}$ aqueous solution of $\mathrm{FeBr}_{3},$ assuming complete dissociation?

Nilay Sebat

Numerade Educator

Problem 3

Three different substances $\mathrm{A}_{2} \mathrm{X}, \mathrm{A}_{2} \mathrm{Y},$ and $\mathrm{A}_{2} \mathrm{Z}$ are dissolved in water, with the following results. (Water molecules are omitted for clarity.) Which of the substances is the strongest electrolyte, and which is the weakest? Explain.

AA

A Adly

Numerade Educator

Problem 4

Write net ionic equations for the following reactions:
(a) $2 \mathrm{AgNO}_{3}(a q)+\mathrm{Na}_{2} \mathrm{CrO}_{4}(a q) \longrightarrow \mathrm{Ag}_{2} \mathrm{CrO}_{4}(s)+2 \mathrm{NaNO}_{3}(a q)$
(b) $\mathrm{H}_{2} \mathrm{SO}_{4}(a q)+\mathrm{MgCO}_{3}(s) \longrightarrow \mathrm{H}_{2} \mathrm{O}(I)+\mathrm{CO}_{2}(g)+\mathrm{MgSO}_{4}(a q)$
(c) $\mathrm{Hg}\left(\mathrm{NO}_{3}\right)_{2}(a q)+2 \mathrm{NH}_{4} \mathrm{I}(a q) \longrightarrow \mathrm{HgI}_{2}(s)+2 \mathrm{NH}_{4} \mathrm{NO}_{3}(a q)$

Nilay Sebat

Numerade Educator

Problem 5

Predict whether each of the following compounds is likely to be soluble in water:
(a) $\mathrm{CdCO}_{3}\quad$ (b) $\mathrm{MgO} \quad$ (c) $\mathrm{Na}_{2} \mathrm{S}$
(d) $\mathrm{PbSO}_{4} \quad$ (e) $\left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4} \quad$ (f) $\mathrm{HgCl}_{2}$

PR

Peter Rivera

Numerade Educator

Problem 6

Predict whether a precipitation reaction will occur in each of the following situations. Write a net ionic equation for each reaction that occurs.
(a) $\mathrm{NiCl}_{2}(a q)+\left(\mathrm{NH}_{4}\right)_{2} \mathrm{S}(a q) \longrightarrow ? \quad$ (b) $\mathrm{Na}_{2} \mathrm{CrO}_{4}(a q)+\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(a q) \longrightarrow ?$
(c) $\mathrm{AgClO}_(a q)+\operatorname{CaBr}_{2}(a q) \longrightarrow ? \quad$ (d) $\mathrm{ZnCl}_{2}(a q)+\mathrm{K}_{2} \mathrm{CO}_{3}(a q) \longrightarrow ?$

Ronald Prasad

Numerade Educator

Problem 7

How might you use a precipitation reaction to prepare a sample of $\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2} ?$ Write the net ionic equation.

Brooke Surin

Numerade Educator

Problem 8

An aqueous solution containing an anion, represented by blue spheres, is added to another solution containing a cation, represented by red spheres, and the following result is obtained. Which cations and anions, chosen from the following lists, are compatible with the observed results?
Anions: $\mathrm{S}^{2-}, \mathrm{PO}_{4}^{3-}, \mathrm{SO}_{4}^{2-}, \mathrm{ClO}_{4}^{-}$
Cations: $\mathrm{Mg}^{2+}, \mathrm{Fe}^{3+}, \mathrm{NH}_{4}^{+}, \mathrm{Zn}^{2+}$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 9

Name the following acids:
(a) $\mathrm{HIO}_{4} \quad$ (b) $\mathrm{HBrO}_{2} \quad$ (c) $\mathrm{H}_{2} \mathrm{CrO}_{4}$

Simon Kangoun

Numerade Educator

Problem 10

Give likely chemical formulas corresponding to the following names:
(a) Phosphorous acid $\quad$ (b) Hydroselenic acid

Nilay Sebat

Numerade Educator

Problem 11

Write a balanced ionic equation and net ionic equation for each of the following acid–base reactions:
(a) $2 \mathrm{CsOH}(a q)+\mathrm{H}_{2} \mathrm{SO}_{4}(a q) \longrightarrow \quad$ (b) $\mathrm{Ca}(\mathrm{OH})_{2}(a q)+2 \mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}(a q) \longrightarrow$

Brooke Surin

Numerade Educator

Problem 12

The following pictures represent aqueous solutions of three acids $\mathrm{HA}(\mathrm{A}=\mathrm{X}, \mathrm{Y}, \text { or } \mathrm{Z})$, with water molecules omitted for clarity. Which of the three is the strongest acid, and which is the weakest?

Nilay Sebat

Numerade Educator

Problem 13

Assign an oxidation number to each atom in the following compounds:
(a) $\mathrm{SnCl}_{4} \quad$ (b) $\mathrm{CrO}_{3} \quad$ (c) $\mathrm{VOCl}_{3}$
(d) $\mathrm{V}_{2} \mathrm{O}_{3} \quad$ (e) $\mathrm{HNO}_{3} \quad$ (f) Feso_ $_{4}$

Simon Kangoun

Numerade Educator

Problem 14

Aqueous copper(II) ion reacts with aqueous iodide ion to yield solid copper(I) iodide and aqueous iodine. Write the balanced net ionic equation, assign oxidation numbers to all species present, and identify the oxidizing and reducing agents.

Ronald Prasad

Numerade Educator

Problem 15

In each of the following reactions, tell which substance is undergoing an oxidation and which a reduction, and identify the oxidizing and reducing agents.
(a) $\mathrm{Sn} \mathrm{O}_{2}(s)+2 \mathrm{C}(s) \longrightarrow \mathrm{Sn}(s)+2 \mathrm{CO}(g)$
(b) $\mathrm{Sn}^{2+}(a q)+2 \mathrm{Fe}^{3+}(a q) \longrightarrow \mathrm{Sn}^{4+}(a q)+2 \mathrm{Fe}^{2+}(a q)$
(c) $4 \mathrm{NH}_{3}(g)+5 \mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{NO}(g)+6 \mathrm{H}_{2} \mathrm{O}(l)$

Brooke Surin

Numerade Educator

Problem 16

Predict whether the following reactions will occur:
(a) $2 \mathrm{H}^{+}(a q)+\mathrm{Pt}(s) \longrightarrow \mathrm{H}_{2}(g)+\mathrm{Pt}^{2+}(a q)$
(b) $\mathrm{Ca}^{2+}(a q)+\mathrm{Mg}(s) \longrightarrow \mathrm{Ca}(s)+\mathrm{Mg}^{2+}(a q)$

Nilay Sebat

Numerade Educator

Problem 17

Element $\mathrm{B}$ will reduce the cation of element $\mathrm{A}\left(\mathrm{A}^{+}\right)$ but will not reduce the cation of element $\mathrm{C}\left(\mathrm{C}^{+}\right)$. Will element $\mathrm{C}$ reduce the cation of element $\mathrm{A}$? Explain.

Simon Kangoun

Numerade Educator

Problem 18

Use the following reactions to arrange the elements $\mathrm{A}, \mathrm{B}, \mathrm{C},$ and $\mathrm{D}$ in order of their redox reactivity from most reactive to least reactive.
$$\mathrm{A}+\mathrm{D}^{+} \longrightarrow \mathrm{A}^{+}+\mathrm{D} \quad\quad\quad\quad \mathrm{C}^{+}+\mathrm{D} \longrightarrow \mathrm{C}+\mathrm{D}^{+}$$
$$\mathrm{B}^{+}+\mathrm{D} \longrightarrow \mathrm{B}+\mathrm{D}^{+} \quad\quad\quad\quad \mathrm{B}+\mathrm{C}^{+} \longrightarrow \mathrm{B}^{+}+\mathrm{C}$$

Brooke Surin

Numerade Educator

Problem 19

Write unbalanced half-reactions for the following net ionic equations:
(a) $\mathrm{MnO}_{4}^{-}(a q)+\mathrm{IO}_{3}^{-}(a q) \longrightarrow \mathrm{MnO}_{2}(s)+\mathrm{IO}_{4}^{-}(a q)$
(b) $\mathrm{NO}_{3}^{-}(a q)+\mathrm{SO}_{2}(a q) \longrightarrow \mathrm{SO}_{4}^{2-}(\mathrm{aq})+\mathrm{NO}_{2}(g)$

Brooke Surin

Numerade Educator

Problem 20

Balance the following net ionic equation by the half-reaction method. The reaction takes place in acidic solution.
$$\mathrm{NO}_{3}^{-}(a q)+\mathrm{Cu}(s) \longrightarrow \mathrm{NO}(g)+\mathrm{Cu}^{2+}(a q) \quad \text { Unbalanced }$$

Nilay Sebat

Numerade Educator

Problem 21

Balance the following equation by the half-reaction method. The reaction takes place in basic solution.
$$\mathrm{Fe}(\mathrm{OH})_{2}(s)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{Fe}(\mathrm{OH})_{3}(s) \quad \text { Unbalanced }$$

Ronald Prasad

Numerade Educator

Problem 22

What is the molar concentration of $\mathrm{Fe}^{2+}$ ion in an aqueous solution if 31.50 $\mathrm{mL}$ of 0.105 $\mathrm{M}$ $\mathrm{KBrO}_{3}$ is required for complete reaction with 10.00 $\mathrm{mL}$ of the $\mathrm{Fe}^{2+}$ solution? The net ionic equation is:
$$6 \mathrm{Fe}^{2+}(a q)+\mathrm{BrO}_{3}^{-}(a q)+6 \mathrm{H}^{+}(a q) \longrightarrow 6 \mathrm{Fe}^{3+}(a q)+\mathrm{Br}^{-}(a q)+3 \mathrm{H}_{2} \mathrm{O}(l)$$

Nilay Sebat

Numerade Educator

Problem 23

In the common lead storage battery used in automobiles, the following two half-reactions occur in acid solution:
$$\text {Oxidation } \quad \mathrm{Pb}(s)+\mathrm{HSO}_{4}^{-(a q)} \longrightarrow \mathrm{PbSO}_{4}(s)$$
$$\text { Reduction} \quad \operatorname{PbO}_{2}(s)+\mathrm{HSO}_{4}^{-(a q)} \longrightarrow \mathrm{PbSO}_{4}(s)$$
Write a balanced equation for the overall battery reaction.

Ronald Prasad

Numerade Educator

Problem 24

Many dozens of different solvents are used in various chemical processes. If you were designing a green process that required a solvent, what properties would you look for, and what solvent might you choose?

Nilay Sebat

Numerade Educator

Problem 25

Assume that an aqueous solution of a cation, represented as a red sphere, is allowed to mix with a solution of an anion, represented as a yellow sphere. Three possible out- comes are represented by boxes (1)–(3):
Which outcome corresponds to each of the following reactions?
(a) $2 \mathrm{Na}^{+}(a q)+\mathrm{CO}_{3}^{2-}(a q) \longrightarrow$
(b) $\mathrm{Ba}^{2+}(a q)+\mathrm{CrO}_{4}^{2-(a q)} \longrightarrow$
(c) $2 \mathrm{Ag}^{+}(a q)+\mathrm{SO}_{3}^{2-}(a q) \longrightarrow$

Simon Kangoun

Numerade Educator

Problem 26

Assume that an aqueous solution of a cation, represented as a blue sphere, is allowed to mix with a solution of an anion, represented as a red sphere, and that the following result is obtained:
Which combinations of cation and anion, chosen from the following lists, are compatible with the observed results? Explain.
$$\text { Cations: } \mathrm{Na}^{+}, \mathrm{Ca}^{2+}, \mathrm{Ag}^{+}, \mathrm{Ni}^{2+}$$
$$\text { Anions: } \mathrm{CI}^{-}, \mathrm{CO}_{3}^{2-}, \mathrm{CrO}_{4}^{2-}, \mathrm{NO}_{3}^{-}$$

Nilay Sebat

Numerade Educator

Problem 27

Assume that an aqueous solution of $\mathrm{OH}^{-},$ represented as a blue sphere, is allowed to mix with a solution of an acid $\mathrm{H}_{n} \mathrm{A},$ represented as a red sphere. Three possible outcomes are depicted by boxes $(1)-(3),$ where the green spheres represent $\mathrm{A}^{n-},$ the anion of the acid:
Which outcome corresponds to each of the following reactions?
(a) $\mathrm{HF}+\mathrm{OH}^{-} \longrightarrow \mathrm{H}_{2} \mathrm{O}+\mathrm{F}^{-}$
(b) $\mathrm{H}_{2} \mathrm{SO}_{3}+2 \mathrm{OH}^{-} \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}+\mathrm{SO}_{3}^{2-}$
(c) $\mathrm{H}_{3} \mathrm{PO}_{4}+3 \mathrm{OH}^{-} \longrightarrow 3 \mathrm{H}_{2} \mathrm{O}+\mathrm{PO}_{4}^{3-}$

Ronald Prasad

Numerade Educator

Problem 28

The concentration of an aqueous solution of $\mathrm{NaOCl}$ (sodium hypochlorite; the active ingredient in household bleach) can be determined by a redox titration with iodide ion in acidic solution:
$$\mathrm{OCl}^{-}(a q)+2 \mathrm{I}^{-}(a q)+2 \mathrm{H}^{+}(a q) \longrightarrow$$
$$\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad {\mathrm{Cl}^{-}(a q)+\mathrm{I}_{2}(a q)+\mathrm{H}_{2} \mathrm{O}(l)}$$
Assume that the blue spheres in the buret represent $\mathrm{I}^{-}$ ions, the red spheres in the flask represent $\mathrm{OCI}^{-}$ ions, the concentration of the $\mathrm{I}^{-}$ ions in the buret is $0.120 \mathrm{M},$ and the volumes in the buret and the flask are identical. What is the concentration of $\mathrm{NaOCl}$ in the flask? What percentage of the $\mathrm{I}^{-}$ solution in the buret must be added to the flask to react with all the $\mathrm{OCI}^{-}$ ions?

Nilay Sebat

Numerade Educator

Problem 29

Assume that the electrical conductivity of a solution depends on the total concentration of dissolved ions and that you measure the conductivity of three different solutions while carrying out titration procedures:
(a) Begin with 1.00 $\mathrm{L}$ of $0.100 \mathrm{M} \mathrm{KCl},$ and titrate by adding 0.100 $\mathrm{M} \mathrm{AgNO}_{3} .$
(b) Begin with 1.00 $\mathrm{L}$ of 0.100 $\mathrm{M} \mathrm{HF}$ , and titrate by adding 0.100 $\mathrm{M} \mathrm{KOH} .$
(c) Begin with 1.00 $\mathrm{L}$ of $0.100 \mathrm{M} \mathrm{BaCl}_{2},$ and titrate by adding 0.100 $\mathrm{M} \mathrm{Na}_{2} \mathrm{SO}_{4}$.
Which of the following graphs corresponds to which titration?

Lottie Adams

Numerade Educator

Problem 30

Based on the positions in the periodic table, which of the following reactions would you expect to occur?
(a) $\operatorname{Red}^{+}+$ Green $\longrightarrow$ Red $+$ Green $^{+}$
(b) Blue $+$ Green $^{+} \longrightarrow$ Blue $^{+}+$ Green
(c) Red $+$ Blue $^{+} \longrightarrow \mathrm{Red}^{+}+$ Blue

Nilay Sebat

Numerade Educator

Problem 31

The following two redox reactions occur between aqueous cations and solid metals. Will a solution of green cations react with solid blue metal? Explain.

Simon Kangoun

Numerade Educator

Problem 32

Classify each of the following reactions as a precipitation, acid–base neutralization, or oxidation–reduction:
(a) $\mathrm{Hg}\left(\mathrm{NO}_{3}\right)_{2}(a q)+2 \mathrm{NaI}(a q) \longrightarrow 2 \mathrm{NaNO}_{3}(a q)+\mathrm{HgI}_{2}(s)$
(b) $2 \mathrm{HgO}(s) \stackrel{\text { heat }}{\longrightarrow} 2 \mathrm{Hg}(l)+\mathrm{O}_{2}(g)$
(c) $\mathrm{H}_{3} \mathrm{PO}_{4}(a q)+3 \mathrm{KOH}(a q) \longrightarrow \mathrm{K}_{3} \mathrm{PO}_{4}(a q)+3 \mathrm{H}_{2} \mathrm{O}(l)$

Nilay Sebat

Numerade Educator

Problem 33

Classify each of the following reactions as a precipitation, acid–base neutralization, or oxidation–reduction:
(a) $\mathrm{S}_{8}(\mathrm{s})+8 \mathrm{O}_{2}(g) \longrightarrow 8 \mathrm{SO}_{2}(g)$
(b) $\mathrm{NiCl}_{2}(a q)+\mathrm{Na}_{2} \mathrm{S}(a q) \longrightarrow \mathrm{NiS}(s)+2 \mathrm{NaCl}(a q)$
(c) $2 \mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}(a q)+\mathrm{Ba}(\mathrm{OH})_{2}(a q) \longrightarrow_{\left(\mathrm{CH}_{3} \mathrm{CO}_{2}\right)_{2} \mathrm{Ba}(a q)+2 \mathrm{H}_{2} \mathrm{O}(l)}$

Ronald Prasad

Numerade Educator

Problem 34

Aqueous Reactions, Net Ionic Equations, and Electrolytes (Sections 4.2 and 4.3 )
Write net ionic equations for the reactions listed in Problem $4.32 .$

Ronald Prasad

Numerade Educator

Problem 35

Write net ionic equations for the reactions listed in Problem 4.33.

Ronald Prasad

Numerade Educator

Problem 36

The following aqueous solutions were tested with a light-bulb conductivity apparatus, as shown in Figure 4.1. What result—dark, dim, or bright—do you expect from each?
(a) 0.10 $\mathrm{M}$ potassium chloride $\quad$ (b) 0.10 $\mathrm{M}$ methanol
(c) 0.10 $\mathrm{M}$ acetic acid

Nilay Sebat

Numerade Educator

Problem 37

The following aqueous solutions were tested with a light-bulb conductivity apparatus, as shown in Figure 4.1. What result—dark, dim, or bright—do you expect from each?
(a) 0.10 $\mathrm{M}$ hydrofluoric acid
(b) 0.10 $\mathrm{M}$ sodium chloride
(c) 0.10 $\mathrm{M}$ glucose $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)$

Simon Kangoun

Numerade Educator

Problem 38

Individual solutions of $\mathrm{Ba}(\mathrm{OH})_{2}$ and $\mathrm{H}_{2} \mathrm{SO}_{4}$ both conduct electricity, but the conductivity disappears when equal molar amounts of the solutions are mixed. Explain.

Nilay Sebat

Numerade Educator

Problem 39

A solution of $\mathrm{HCl}$ in water conducts electricity, but a solution of $\mathrm{HCl}$ in chloroform, $\mathrm{CHCl}$, does not. What does this observation tell you about how $\mathrm{HCl}$ exists in water and how it exists in chloroform?

Simon Kangoun

Numerade Educator

Problem 40

Classify each of the following substances as either a strong electrolyte, weak electrolyte, or nonelectrolyte:
(a) $\mathrm{HBr} \quad\quad\quad\quad$ (b) $\mathrm{HF} \quad\quad$ (c) $\mathrm{NaClO}_{4}$
(d) $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3} \quad$ (e) $\mathrm{NH}_{3} \quad$ (f) Ethyl alcohol

Nilay Sebat

Numerade Educator

Problem 41

Is it possible for a molecular substance to be a strong electrolyte? Explain.

Simon Kangoun

Numerade Educator

Problem 42

What is the total molar concentration of ions in each of the following solutions, assuming complete dissociation?
(a) A 0.750 $\mathrm{M}$ solution of $\mathrm{K}_{2} \mathrm{CO}_{3}$
(b) A 0.355 $\mathrm{M}$ solution of $\mathrm{AlCl}_{3}$

Nilay Sebat

Numerade Educator

Problem 43

What is the total molar concentration of ions in each of the following solutions?
(a) A 1.250 $\mathrm{M}$ solution of $\mathrm{CH}_{3} \mathrm{OH}$
(b) A 0.225 $\mathrm{M}$ solution of $\mathrm{HClO}_{4}$

Simon Kangoun

Numerade Educator

Problem 44

Which of the following substances are likely to be soluble in water?
(a) $\mathrm{Ag}_{2} \mathrm{O} \quad$ (b) $\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}\quad$ (c) $\mathrm{SnCO}_{3} \quad$ (d) $\mathrm{Fe}_{2} \mathrm{O}_{3}$

Nilay Sebat

Numerade Educator

Problem 45

Which of the following substances are likely to be soluble in water?
(a) $\mathrm{ZnS} \quad$ (b) $\mathrm{Au}_{2}\left(\mathrm{CO}_{3}\right)_{3} \quad$ (c) $\mathrm{PbCl}_{2} \quad$ (d) $\mathrm{MnO}_{2}$

Simon Kangoun

Numerade Educator

Problem 46

Predict whether a precipitation reaction will occur when aqueous solutions of the following substances are mixed:
(a) $\mathrm{NaOH} + \mathrm{HCIO}_{4} \quad\quad$ (b) $\mathrm{FeCl}_{2}+\mathrm{KOH}$
(c) $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}+\mathrm{NiCl}_{2} \quad$ (d) $\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{Na}+\mathrm{HCl}$

Nilay Sebat

Numerade Educator

Problem 47

Predict whether a precipitation reaction will occur when aqueous solutions of the following substances are mixed:
(a) $\mathrm{MnCl}_{2}+\mathrm{Na}_{2} \mathrm{S} \quad\quad\quad$ (b) $\mathrm{HNO}_{3}+\mathrm{CuSO}_{4}$
(c) $\mathrm{Hg(NO}_{3} )_{2}+\mathrm{Na_{3 }} \mathrm{PO}_{4} \quad$ (d) $\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}+\mathrm{KOH}$

Simon Kangoun

Numerade Educator

Problem 48

Which of the following solutions will not form a precipitate when added to 0.10 $\mathrm{M} $ $\mathrm{BaCl}_{2} ?$
(a) 0.10 $\mathrm{M} \mathrm{LiNO}_{3} \quad$ (b) 0.10 $\mathrm{M} \mathrm{K}_{2} \mathrm{SO}_{4} \quad$ (c) 0.10 $\mathrm{M} \mathrm{AgNO}_{3}$

Simon Kangoun

Numerade Educator

Problem 49

Which of the following solutions will not form a precipitate when added to 0.10 $\mathrm{M} $ $\mathrm{NaOH}$ ?
(a) 0.10 $\mathrm{MMgBr}_{2} \quad$ (b) 0.10 $\mathrm{M} \mathrm{NH}_{4} \mathrm{Br} \quad$ (c) 0.10 $\mathrm{M} \mathrm{FeCl}_{2}$

Ronald Prasad

Numerade Educator

Problem 50

How would you prepare the following substances by a precipitation reaction?
(a) $\mathrm{PbSO}_{4} \quad$ (b) $\mathrm{Mg}_{3}\left(\mathrm{PO}_{4}\right)_{2} \quad$ (c) $\mathrm{ZnCrO}_{4}$

Ronald Prasad

Numerade Educator

Problem 51

How would you prepare the following substances by a precipitation reaction?
(a) $\mathrm{Al}(\mathrm{OH})_{3} \quad$ (b) $\mathrm{FeS} \quad$ (c) $\mathrm{CoCO}_{3}$

Ronald Prasad

Numerade Educator

Problem 52

Assume that you have an aqueous mixture of $\mathrm{NaNO}_{3}$ and $\mathrm{AgNO}_{3}$. How could you use a precipitation reaction to separate the two metal ions?

Ronald Prasad

Numerade Educator

Problem 53

Assume that you have an aqueous mixture of $\mathrm{BaCl}_{2}$ and $\mathrm{CuCl}_{2}$. How could you use a precipitation reaction to separate the two metal ions?

Ronald Prasad

Numerade Educator

Problem 54

Assume that you have an aqueous solution of an unknown salt. Treatment of the solution with dilute $\mathrm{NaOH}, \mathrm{Na}_{2} \mathrm{SO}_{4}$, and $\mathrm{KCl}$ produces no precipitate. Which of the following cations might the solution contain?
(a) $\mathrm{Ag}^{+} \quad$ (b) $\mathrm{Cs}^{+} \quad$ (c) $\mathrm{Ba}^{2+} \quad$ (d) $\mathrm{NH}_{4}^{+}$

Ronald Prasad

Numerade Educator

Problem 55

Assume that you have an aqueous solution of an unknown salt. Treatment of the solution with dilute $\mathrm{BaCl}_{2}, \mathrm{AgNO}_{3}$, and $\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}$ produces no precipitate. Which of the following anions might the solution contain?
(a) $\mathrm{Cl}^{-} \quad$ (b) $\mathrm{NO}_{3}^{-} \quad$ (c) $\mathrm{OH}^{-}$ $\quad$ (d) $\mathrm{SO}_{4}^{2-}$

Ronald Prasad

Numerade Educator

Problem 56

Assume that you are given a solution of an unknown acid or base. How can you tell whether the unknown substance is acidic or basic?

Nilay Sebat

Numerade Educator

Problem 57

Why do we use a double arrow ( $\rightleftharpoons$ ) to show the dissociation of a weak acid or weak base in aqueous solution?

Ronald Prasad

Numerade Educator

Problem 58

Write balanced ionic equations for the following reactions:
(a) Aqueous perchloric acid is neutralized by aqueous calcium hydroxide.
(b) Aqueous sodium hydroxide is neutralized by aqueous acetic acid.

Ronald Prasad

Numerade Educator

Problem 59

Write balanced ionic equations for the following reactions:
(a) Aqueous hydrobromic acid is neutralized by aqueous calcium hydroxide.
(b) Aqueous barium hydroxide is neutralized by aqueous nitric acid.

Ronald Prasad

Numerade Educator

Problem 60

Write balanced net ionic equations for the following reactions:
(a) $\mathrm{LiOH}(a q)+\mathrm{HI}(a q) \longrightarrow ?$
(b) $\mathrm{HBr}(a q)+\mathrm{Ca}(\mathrm{OH})_{2}(a q) \longrightarrow ?$

Ronald Prasad

Numerade Educator

Problem 61

Write balanced net ionic equations for the following reactions. Note that $\mathrm{HClO}_{3}$ is a strong acid.
(a) $\mathrm{Fe}(\mathrm{OH})_{3}(s)+\mathrm{H}_{2} \mathrm{SO}_{4}(a q) \longrightarrow ?$
(b) $\mathrm{HClO}_{3}(a q)+\mathrm{NaOH}(a q) \longrightarrow ?$

Ronald Prasad

Numerade Educator

Problem 62

If the following solutions are mixed, is the resulting solution acidic, basic, or neutral?
(a) 50.0 $\mathrm{mL}$ of 0.100 $\mathrm{M} \mathrm{HBr}$ and 30.0 $\mathrm{mL}$ of 0.200 $\mathrm{M} \mathrm{KOH}$
(b) 100.0 $\mathrm{mL}$ of 0.0750 $\mathrm{M} \mathrm{HCl}$ and 75.0 $\mathrm{mL}$ of 0.100 $\mathrm{M}$$\mathrm{Ba}(\mathrm{OH})_{2}$

Ronald Prasad

Numerade Educator

Problem 63

If the following solutions are mixed, is the resulting solution acidic, basic, or neutral?
(a) 65.0 $\mathrm{mL}$ of 0.0500 $\mathrm{M} \mathrm{HClO}_{4}$ and 40.0 $\mathrm{mL}$ of 0.0750 $\mathrm{M}$
(b) 125.0 $\mathrm{mL}$ of 0.100 $\mathrm{M} \mathrm{HNO}_{3}$ and 90.0 $\mathrm{mL}$ of 0.0750 $\mathrm{M}$ $\mathrm{Ca}(\mathrm{OH})_{2}$

Ronald Prasad

Numerade Educator

Problem 64

How many milliliters of 1.00 $\mathrm{M} \mathrm{KOH}$ must be added to neutralize the following solutions?
(a) a mixture of 0.240 $\mathrm{M}$ LiOH $(25.0 \mathrm{mL})$ and 0.200 $\mathrm{M}$ HBr $(75.0 \mathrm{mL})$
(b) a mixture of 0.300 $\mathrm{M} \mathrm{HCl}(45.0 \mathrm{mL})$ and 0.250 $\mathrm{M} \mathrm{NaOH}$ $(10.0 \mathrm{mL})$

Anand Jangid

Numerade Educator

Problem 65

How many milliters of 2.00 $\mathrm{M} \mathrm{HCl}$ must be added to neutralize the following solutions?
(a) a mixture of 0.160 $\mathrm{M} \mathrm{HNO}_{3}(100.0 \mathrm{mL})$ and 0.100 $\mathrm{M}$ $\mathrm{KOH}$ $(400.0 \mathrm{mL})$
(b) a mixture of 0.120 $\mathrm{M} \mathrm{NaOH}(350.0 \mathrm{mL})$ and 0.190 $\mathrm{M}$ $\mathrm{HBr}$ (150.0 $\mathrm{mL} )$

Ronald Prasad

Numerade Educator

Problem 66

Where in the periodic table are the best reducing agents found? The best oxidizing agents?

Brooke Surin

Numerade Educator

Problem 67

Where in the periodic table are the most easily reduced elements found? The most easily oxidized?

Ronald Prasad

Numerade Educator

Problem 68

In each of the following instances, tell whether the substance gains electrons or loses electrons in a redox reaction:
(a) An oxidizing agent
(b) A reducing agent
(c) A substance undergoing oxidation
(d) A substance undergoing reduction

Nilay Sebat

Numerade Educator

Problem 69

Tell for each of the following substances whether the oxidation number increases or decreases in a redox reaction:
(a) An oxidizing agent
(b) A reducing agent
(c) A substance undergoing oxidation
(d) A substance undergoing reduction

Ronald Prasad

Numerade Educator

Problem 70

Assign oxidation numbers to each element in the following compounds:
(a) $\mathrm{NO}_{2} \quad$ (b) $\mathrm{SO}_{3} \quad$ (c) $\mathrm{COCl}_{2}$
(d) $\mathrm{CH}_{2} \mathrm{Cl}_{2} \quad$ (e) $\mathrm{KClO}_{3} \quad$ (f) $\mathrm{HNO}_{3}$

Ronald Prasad

Numerade Educator

Problem 71

Assign oxidation numbers to each element in the following compounds:
(a) $\mathrm{VOCl}_{3} \quad$ (b) $\mathrm{CuSO}_{4} \quad$ (c) $\mathrm{CH}_{2} \mathrm{O}$
(d) $\mathrm{Mn}_{2} \mathrm{O}_{7} \quad$ (e) $\mathrm{OsO}_{4} \quad$ (f) $\mathrm{H}_{2} \mathrm{PtCl}_{6}$

Ronald Prasad

Numerade Educator

Problem 72

Assign oxidation numbers to each element in the following ions:
(a) $\mathrm{ClO}_{3}^{-} \quad$ (b) $\mathrm{SO}_{3}^{2-} \quad$ (c) $\mathrm{C}_{2} \mathrm{O}_{4}^{2-}$
(d) $\mathrm{NO}_{2}^{-} \quad$ (e) $\mathrm{BrO}^{-} \quad$ (f) $\mathrm{AsO}_{4}^{3-}$

Ronald Prasad

Numerade Educator

Problem 73

Assign oxidation numbers to each element in the following ions:
(a) $\mathrm{Cr}(\mathrm{OH})_{4}^{-} \quad$ (b) $\mathrm{S}_{2} \mathrm{O}_{3}^{2-} \quad$ (c) $\mathrm{NO}_{3}-$
(d) $\mathrm{MnO}_{4}^{2-} \quad$ (e) $\mathrm{HPO}_{4}^{2-} \quad$ (f) $\mathrm{V}_{2} \mathrm{O}_{7}^{4-}$

Ronald Prasad

Numerade Educator

Problem 74

Which element is oxidized and which is reduced in each of the following reactions?
(a) $\mathrm{Ca}(s)+\mathrm{Sn}^{2+}(a q) \longrightarrow \mathrm{Ca}^{2+}(a q)+\mathrm{Sn}(s)$
(b) ICl(s) $+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{HCl}(a q)+\mathrm{HOI}(a q)$

Nilay Sebat

Numerade Educator

Problem 75

Which element is oxidized and which is reduced in each of the following reactions?
(a) $\mathrm{Si}(s)+2 \mathrm{Cl}_{2}(g) \longrightarrow \mathrm{SiCl}_{4}(l)$
(b) $\mathrm{Cl}_{2}(g)+2 \mathrm{NaBr}(a q) \longrightarrow \mathrm{Br}_{2}(a q)+2 \mathrm{NaCl}(a q)$

Ronald Prasad

Numerade Educator

Problem 76

Use the activity series of metals (Table 4.5; page 130) to predict the outcome of each of the following reactions. If no reaction occurs, write N.R.
(a) $\mathrm{Na}^{+}(a q)+\mathrm{Zn}(s) \longrightarrow ? \quad$ (b) $\mathrm{HCl}(a q)+\mathrm{Pt}(s) \longrightarrow ?$
(c) $\mathrm{Ag}^{+}(a q)+\mathrm{Au}(s) \longrightarrow ?$ (d) $\mathrm{Au}^{3+}(a q)+\mathrm{Ag}(s) \longrightarrow ?$

Ronald Prasad

Numerade Educator

Problem 77

Neither strontium (Sr) nor antimony (Sb) is shown in the activity series of Table 4.5. Based on their positions in the periodic table, which would you expect to be the better reducing agent? Will the following reaction occur? Explain.
$$2 \mathrm{Sb}^{3+}(a q)+3 \mathrm{Sr}(s) \longrightarrow 2 \mathrm{Sb}(s)+3 \mathrm{Sr}^{2+}(a q)$$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 78

(a) Use the following reactions to arrange the elements A,B, C, and D in order of their decreasing ability as reducing agents:
$$\mathrm{A}+\mathrm{B}^{+} \longrightarrow \mathrm{A}^{+}+\mathrm{B} \quad \mathrm{C}^{+}+\mathrm{D} \longrightarrow \text { no reaction}$$
$$\mathrm{B}+\mathrm{D}^{+} \longrightarrow \mathrm{B}^{+}+\mathrm{D} \quad \mathrm{B}+\mathrm{C}^{+} \longrightarrow \mathrm{B}^{+}+\mathrm{C}$$
(b) Which of the following reactions would you expect to occur according to the activity series you established in part (a)?
$$\text { (1) } \mathrm{A}^{+}+\mathrm{C} \longrightarrow \mathrm{A}+\mathrm{C}^{+} \text { (2) }\mathrm{A}^{+}+\mathrm{D} \longrightarrow \mathrm{A}+\mathrm{D}^{+}$$

Ronald Prasad

Numerade Educator

Problem 79

(a) Use the following reactions to arrange the elements A,B, C, and D in order of their decreasing ability as reducing agents:
$$2 \mathrm{A}+\mathrm{B}^{2+} \longrightarrow 2 \mathrm{A}^{+}+\mathrm{B} \quad \mathrm{B}+\mathrm{D}^{2+} \longrightarrow \mathrm{B}^{2+}+\mathrm{D}$$
$$\mathrm{A}^{+}+\mathrm{C} \longrightarrow \text { no reaction} \quad 2 \mathrm{C}+\mathrm{B}^{2+} \longrightarrow 2 \mathrm{C}^{+}+\mathrm{B}$$
(b) Which of the following reactions would you expect to occur according to the activity series you established in part (a)?
(1) $2 \mathrm{A}^{+}+\mathrm{D} \longrightarrow 2 \mathrm{A}+\mathrm{D}^{2+}$
(2) $\mathrm{D}^{2+}+2 \mathrm{C} \longrightarrow \mathrm{D}+2 \mathrm{C}^{+}$

Ronald Prasad

Numerade Educator

Problem 80

Classify each of the following unbalanced half-reactions as either an oxidation or a reduction:
(a) $\mathrm{NO}_{3}^{-}(a q) \longrightarrow \mathrm{NO}(g) \quad$ (b) $\mathrm{Zn}(s) \longrightarrow \mathrm{Zn}^{2+}(a q)$
(c) $\mathrm{Ti}^{3+}(a q) \longrightarrow \mathrm{TiO}_{2}(s) \quad$ (d) $\mathrm{Sn}^{4+}(a q) \longrightarrow \mathrm{Sn}^{2+}(a q)$

Nilay Sebat

Numerade Educator

Problem 81

Classify each of the following unbalanced half-reactions as either an oxidation or a reduction:
(a) $\mathrm{O}_{2}(g) \longrightarrow \mathrm{OH}^{-}(a q) \quad_{2}$ (b) $\mathrm{H}_{2} \mathrm{O}_{2}(a q) \longrightarrow \mathrm{O}_{2}(g)$
(c) $\mathrm{MnO}_{4}^{-}(a q) \longrightarrow \mathrm{MnO}_{4}^{2-}(a q)$
(d) $\mathrm{CH}_{3} \mathrm{OH}(a q) \longrightarrow \mathrm{CH}_{2} \mathrm{O}(a q)$

Ronald Prasad

Numerade Educator

Problem 82

Balance the half-reactions in Problem 4.80, assuming that they occur in acidic solution.

Ronald Prasad

Numerade Educator

Problem 83

Balance the half-reactions in Problem 4.81, assuming that they occur in basic solution.

Ronald Prasad

Numerade Educator

Problem 84

Write unbalanced oxidation and reduction half-reactions for the following processes:
(a) $\mathrm{Te}(s)+\mathrm{NO}_{3}^{-}(a q) \longrightarrow \mathrm{TeO}_{2}(s)+\mathrm{NO}(g)$
(b) $\mathrm{H}_{2} \mathrm{O}_{2}(a q)+\mathrm{Fe}^{2+}(a q) \longrightarrow \mathrm{Fe}^{3+}(a q)+\mathrm{H}_{2} \mathrm{O}(l)$

Ronald Prasad

Numerade Educator

Problem 85

Write unbalanced oxidation and reduction half-reactions for the following processes:
(a) $\mathrm{Mn}(s)+\mathrm{NO}_{3}^{-(a q)} \longrightarrow \mathrm{Mn}^{2+}(a q)+\mathrm{NO}_{2}(g)$
(b) $\mathrm{Mn}^{3+}(a q) \longrightarrow \mathrm{MnO}_{2}(s)+\mathrm{Mn}^{2+}(a q)$

Ronald Prasad

Numerade Educator

Problem 86

Balance the following half-reactions:
(a) (acidic) $\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q) \longrightarrow \mathrm{Cr}^{3+}(a q)$
(b) (basic) $\mathrm{CrO}_{4}^{2-}(a q) \longrightarrow \mathrm{Cr}(\mathrm{OH})_{4}^{-}(a q)$
(c) (basic) $\mathrm{Bi}^{3+}(a q) \longrightarrow \mathrm{BiO}_{3}(a q)$
(d) (basic) $\mathrm{ClO}^{-}(a q) \longrightarrow \mathrm{Cl}^{-}(a q)$

Ronald Prasad

Numerade Educator

Problem 87

Balance the following half-reactions:
(a) (acidic) $\mathrm{VO}^{2+}(a q) \longrightarrow \mathrm{V}^{3+}(a q)$
(b) (basic) $\mathrm{Ni}(\mathrm{OH})_{2}(s) \longrightarrow \mathrm{Ni}_{2} \mathrm{O}_{3}(s)$
(c) (acidic) $\mathrm{NO}_{3}^{-}(a q) \longrightarrow \mathrm{NO}_{2}(a q)$
(d) (basic) $\mathrm{Br}_{2}(a q) \longrightarrow \mathrm{BrO}_{3}^{-}(a q)$

Ronald Prasad

Numerade Educator

Problem 88

Write balanced net ionic equations for the following reactions in basic solution:
(a) $\mathrm{MnO}_{4}^{-}(a q)+\mathrm{IO}_{3}^{-}(a q) \longrightarrow \mathrm{MnO}_{2}(s)+\mathrm{IO}_{4}^{-}(a q)$
(b) $\mathrm{Cu}(\mathrm{OH})_{2}(\mathrm{s})+\mathrm{N}_{2} \mathrm{H}_{4}(a q) \longrightarrow \mathrm{Cu}(s)+\mathrm{N}_{2}(g)$
(c) $\mathrm{Fe}(\mathrm{OH})_{2}(s)+\mathrm{CrO}_{4}^{2-}(a q) \longrightarrow_{\mathrm{Fe}(\mathrm{OH})_{3}(s)}+\mathrm{Cr}(\mathrm{OH})_{4}^{-}(a q)$
(d) $\mathrm{H}_{2} \mathrm{O}_{2}(a q)+\mathrm{ClO}_{4}^{-(a q)} \longrightarrow \mathrm{ClO}_{2}^{-(a q)}+\mathrm{O}_{2}(g)$

Ronald Prasad

Numerade Educator

Problem 89

Write balanced net ionic equations for the following reactions in basic solution:
(a) $\mathrm{S}_{2} \mathrm{O}_{3}^{2-}(a q)+\mathrm{I}_{2}(a q) \longrightarrow \mathrm{S}_{4} \mathrm{O}_{6}^{2-}(a q)+\mathrm{I}^{-}(a q)$
(b) $\mathrm{Mn}^{2+}(a q)+\mathrm{H}_{2} \mathrm{O}_{2}(a q) \longrightarrow \mathrm{MnO}_{2}(s)+\mathrm{H}_{2} \mathrm{O}(l)$
(c) $\mathrm{Zn}(s)+\mathrm{NO}_{3}^{-}(a q) \longrightarrow \mathrm{NH}_{3}(a q)+\mathrm{Zn}(\mathrm{OH})_{4}^{2-}(a q)$
(d) $\mathrm{Bi}(\mathrm{OH})_{3}(s)+\mathrm{Sn}(\mathrm{OH})_{3}^{-}(a q) \longrightarrow \mathrm{Bi}(s)+\mathrm{Sn}(\mathrm{OH})_{6}^{2-}(a q)$

Ronald Prasad

Numerade Educator

Problem 90

Write balanced net ionic equations for the following reactions in acidic solution:
(a) $\mathrm{Zn}(s)+\mathrm{VO}^{2+}(\mathrm{aq}) \longrightarrow \mathrm{Zn}^{2+}(a q)+\mathrm{V}^{3+}(a q)$
(b) $\mathrm{Ag}(s)+\mathrm{NO}_{3}^{-}(a q) \longrightarrow \mathrm{Ag}^{+}(a q)+\mathrm{NO}_{2}(g)$
(c) $\mathrm{Mg}(s)+\mathrm{VO}_{4}^{3-}(a q) \longrightarrow \mathrm{Mg}^{2+}(a q)+\mathrm{V}^{2+}(a q)$
(d) I $(a q)+\mathrm{IO}_{3}^{-}(a q) \longrightarrow \mathrm{I}_{3}^{-}(a q)$

Ronald Prasad

Numerade Educator

Problem 91

Write balanced net ionic equations for the following reactions in acidic solution:
(a) $\operatorname{MnO}_{4}^{-(a q)}+\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(a q) \longrightarrow _{\operatorname{mn}^{2+}(a q)+\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}(a q)}$
(b) $\mathrm{H}_{2} \mathrm{O}_{2}(a q)+\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q) \longrightarrow \mathrm{O}_{2}(g)+\mathrm{Cr}^{3+}(a q)$
(c) $\mathrm{Sn}^{2+}(a q)+\mathrm{IO}_{4}^{-}(a q) \longrightarrow \mathrm{Sn}^{4+}(a q)+\mathrm{I}^{-}(a q)$
(d) $\mathrm{PbO}_{2}(s)+\mathrm{Cl}^{-}(a q) \longrightarrow \mathrm{PbCl}_{2}(s)+\mathrm{O}_{2}(g)$

Ronald Prasad

Numerade Educator

Problem 92

Iodine, $\mathrm{I}_{2},$ reacts with aqueous thiosulfate ion in neutral solution according to the balanced equation
$$\mathrm{I}_{2}(a q)+2 \mathrm{S}_{2} \mathrm{O}_{3}^{2-}(a q) \longrightarrow \mathrm{S}_{4} \mathrm{O}_{6}^{2-}(a q)+2 \Gamma(a q)$$
How many grams of $\mathrm{I}_{2}$ are present in a solution if 35.20 $\mathrm{mL}$ of 0.150 $\mathrm{M} \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}$ solution is needed to titrate the $\mathrm{I}_{2}$ solution?

Ronald Prasad

Numerade Educator

Problem 93

How many milliliters of 0.250 $\mathrm{M} \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}$ solution is needed for complete reaction with 2.486 $\mathrm{g}$ of $\mathrm{I}_{2}$ according to the equation in Problem 4.92$?$

Ronald Prasad

Numerade Educator

Problem 94

Dichromate ion, $\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-},$ reacts with aqueous iron(\PiI) ion in acidic solution according to the balanced equation
$$\begin{array}{rl}{\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)+6 \mathrm{Fe}^{2+}(a q)} & {+14 \mathrm{H}^{+}(a q) \longrightarrow} \\ {2} & {\mathrm{Cr}^{3+}(a q)+6 \mathrm{Fe}^{3+}(a q)+7 \mathrm{H}_{2} \mathrm{O}(l)}\end{array}$$
What is the concentration of $\mathrm{Fe}^{2+}$ if 46.99 $\mathrm{mL}$ of 0.2004 $\mathrm{M}$ $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ is needed to titrate 50.00 $\mathrm{mL}$ of the $\mathrm{Fe}^{2+}$ solution?

Ronald Prasad

Numerade Educator

Problem 95

A volume of 18.72 $\mathrm{mL}$ of 0.1500 $\mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ solution was required to titrate a sample of $\mathrm{FeSO}_{4}$ according to the equation in Problem $4.94 .$ What is the mass of the sample?

Ronald Prasad

Numerade Educator

Problem 96

What is the molar concentration of As(III) in a solution if 22.35 $\mathrm{mL}$ of 0.100 $\mathrm{M} \mathrm{KBrO}_{3}$ is needed for complete reaction with 50.00 $\mathrm{mL}$ of the As (III) solution? The balanced equation is:
$$3 \mathrm{H}_{3} \mathrm{AsO}_{3}(a q)+\mathrm{BrO}_{3}^{-}(a q) \longrightarrow \mathrm{Br}^{-}(a q)+3 \mathrm{H}_{3} \mathrm{AsO}_{4}(a q)$$

Ronald Prasad

Numerade Educator

Problem 97

Standardized solutions of $\mathrm{KBrO}_{3}$ are frequently used in redox titrations. The necessary solution can be made by dissolving $\mathrm{KBrO}_{3}$ in water and then titrating it with an As (III) solution. What is the molar concentration of a $\mathrm{KBrO}_{3}$ solution if 28.55 $\mathrm{mL}$ of the solution is needed to titrate 1.550 $\mathrm{g}$ of $\mathrm{As}_{2} \mathrm{O}_{3} ?$ See Problem 4.96 for the balanced equation. $\left(\mathrm{As}_{2} \mathrm{O}_{3} \text { dissolves in aqueous acid solution to }\right.$ yield $\mathrm{H}_{3} \mathrm{AsO}_{3} : \mathrm{As}_{2} \mathrm{O}_{3}+3 \mathrm{H}_{2} \mathrm{O} \longrightarrow 2 \mathrm{H}_{3} \mathrm{AsO}_{3} )$

Ronald Prasad

Numerade Educator

Problem 98

The metal content of iron in ores can be determined by a redox procedure in which the sample is first oxidized with $\mathrm{Br}_{2}$ to convert all the iron to $\mathrm{Fe}^{3+}$ and then titrated with $\mathrm{Sn}^{2+}$ to reduce the $\mathrm{Fe}^{3+}$ to $\mathrm{Fe}^{2+} .$ The balanced equation is:
$$2 \mathrm{Fe}^{3+}(a q)+\mathrm{Sn}^{2+}(a q) \longrightarrow 2 \mathrm{Fe}^{2+}(a q)+\mathrm{Sn}^{4+}(a q)$$
What is the mass percent Fe in a 0.1875 g sample of ore if 13.28 $\mathrm{mL}$ of a 0.1015 $\mathrm{M} \mathrm{Sn}^{2+}$ solution is needed to titrate the $\mathrm{Fe}^{3+} ?$

Ronald Prasad

Numerade Educator

Problem 99

The concentration of the $\mathrm{Sn}^{2+}$ solution used in Problem 4.98 can be found by letting it react with a known amount of $\mathrm{Fe}^{3+}$ . What is the molar concentration of an $\mathrm{Sn}^{2+}$ solution if 23.84 $\mathrm{mL}$ is required for complete reaction with 1.4855 $\mathrm{g}$ of $\mathrm{Fe}_{2} \mathrm{O}_{3} ?$

Ronald Prasad

Numerade Educator

Problem 100

Alcohol levels in blood can be determined by a redox reaction with potassium dichromate according to the balanced equation
$\begin{array}{rl}{\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(a q)+2 \mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)+16 \mathrm{H}^{+}(a q)} \longrightarrow \\ {2} & {\mathrm{CO}_{2}(g)+4 \mathrm{Cr}^{3+}(a q)+11 \mathrm{H}_{2} \mathrm{O}(l)}\end{array}$
What is the blood alcohol level in mass percent if 8.76 $\mathrm{mL}$ of 0.04988 $\mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ is required for complete reaction with a 10.002 $\mathrm{g}$ sample of blood?

Ronald Prasad

Numerade Educator

Problem 101

Calcium levels in blood can be determined by adding oxalate ion to precipitate calcium oxalate, $\mathrm{CaC}_{2} \mathrm{O}_{4},$ followed by dissolving the precipitate in aqueous acid and titrating the resulting oxalic acid $\left(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}\right)$ with $\mathrm{KMnO}_{4}$
$$\begin{aligned} 5 \mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}(a q)+2 \mathrm{MnO}_{4}^{-}(a q)+6 \mathrm{H}^{+}(a q) \longrightarrow & \\ & 10 \mathrm{CO}_{2}(g)+2 \mathrm{Mn}^{2+}(a q)+8 \mathrm{H}_{2} \mathrm{O}(l) \end{aligned}$$
How many milligrams of $\mathrm{Ca}^{2+}$ are present in 10.0 $\mathrm{mL}$ of blood if 21.08 $\mathrm{mL}$ of 0.000988 $\mathrm{M} \mathrm{M} \mathrm{MnO}_{4}$ solution is needed for the titration?

Ronald Prasad

Numerade Educator

Problem 102

Balance the equations for the following reactions in basic solution:
(a) $\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-}(a q)+\mathrm{N}_{2} \mathrm{H}_{4}(a q) \longrightarrow\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4-}(a q)+\mathrm{N}_{2}(g)$
(b) $\operatorname{SeO}_{3}^{2-}(a q)+\mathrm{Cl}_{2}(g) \longrightarrow \mathrm{SeO}_{4}^{2-}(a q)+\mathrm{Cl}^{-}(a q)$
(c) $\mathrm{Co}^{2+}(a q)+\mathrm{HO}_{2}^{-}(a q) \longrightarrow \mathrm{Co}(\mathrm{OH})_{3}(s)$

Ronald Prasad

Numerade Educator

Problem 103

An alternative procedure to that given in Problem 4.98 for determining the amount of iron in a sample is to convert the iron to $\mathrm{Fe}^{2+}$ and then titrate it with a solution of $\mathrm{Ce}\left(\mathrm{NH}_{4}\right)_{2}\left(\mathrm{NO}_{3}\right)_{6}$
$$\mathrm{Fe}^{2+}(a q)+\mathrm{Ce}^{4+}(a q) \longrightarrow \mathrm{Fe}^{3+}(a q)+\mathrm{Ce}^{3+}(a q)$$
What is the mass percent of iron in a sample if 1.2284 g of the sample requires 57.91 $\mathrm{mL}$ of 0.1018 $\mathrm{M} \mathrm{Ce}\left(\mathrm{NH}_{4}\right)_{2}\left(\mathrm{NO}_{3}\right)_{6}$ for complete reaction?

Ronald Prasad

Numerade Educator

Problem 104

Assign oxidation numbers to each atom in the following substances:
(a) Ethane, $\mathrm{C}_{2} \mathrm{H}_{6}$ a constituent of natural gas
(b) Borax, $\mathrm{Na}_{2} \mathrm{B}_{4} \mathrm{O}_{7},$ a mineral used in laundry detergents
(c) $\mathrm{Mg}_{2} \mathrm{Si}_{2} \mathrm{O}_{6},$ a silicate mineral

Ronald Prasad

Numerade Educator

Problem 105

Balance the equations for the following reactions in acidic solution:
(a) $\mathrm{PbO}_{2}(s)+\mathrm{Mn}^{2+}(a q) \longrightarrow \mathrm{Pb}^{2+}(a q)+\mathrm{MnO}_{4}^{-(a q)}$
(b) $\mathrm{As}_{2} \mathrm{O}_{3}(s)+\mathrm{NO}_{3}^{-}(a q) \longrightarrow \mathrm{H}_{3} \mathrm{AsO}_{4}(a q)+\mathrm{HNO}_{2}(a q)$
(c) $\mathrm{Br}_{2}(a q)+\mathrm{SO}_{2}(g) \longrightarrow \mathrm{Br}^{-}(a q)+\mathrm{HSO}_{4}^{-}(a q)$
(d) $\mathrm{NO}_{2}^{-}(a q)+\mathrm{I}^{-}(a q) \longrightarrow \mathrm{I}_{2}(s)+\mathrm{NO}(g)$

Ronald Prasad

Numerade Educator

Problem 106

(a) Use the following reactions to arrange the elements A, B, C, and D in order of their decreasing ability as reducing agents:
$$\mathrm{C}+\mathrm{B}^{+} \longrightarrow \mathrm{C}^{+}+\mathrm{B} \quad \mathrm{A}^{+}+\mathrm{D} \longrightarrow \text {No reaction}$$
$$\mathrm{C}^{+}+\mathrm{A} \longrightarrow \text {No reaction} \quad \mathrm{D}+\mathrm{B}^{+} \longrightarrow \mathrm{D}^{+}+\mathrm{B}$$
(b) Which of the following reactions would you expect to occur according to the activity series you established in part (a)?
(1) $\mathrm{A}^{+}+\mathrm{C} \longrightarrow \mathrm{A}+\mathrm{C}^{+}$
(2) $\mathrm{A}^{+}+\mathrm{B} \longrightarrow \mathrm{A}+\mathrm{B}^{+}$

Ronald Prasad

Numerade Educator

Problem 107

Some metals occur naturally in their elemental state while others occur as compounds in ores. Gold, for instance, is found as the free metal; mercury is obtained by heating mercury(II) sulfide ore in oxygen; and zinc is obtained by heating zinc(II) oxide ore with coke (carbon). Judging from their positions in the activity series, which of the metals silver, platinum, and chromium would probably be obtained by
(a) finding it in its elemental state
(b) heating its sulfide with oxygen
(c) heating its oxide with coke

Ronald Prasad

Numerade Educator

Problem 108

A sample weighing 14.98 g and containing a small amount of copper was treated to give a solution containing aqueous $\mathrm{Cu}^{2+}$ ions. Sodium iodide was then added to yield solid copper(l) iodide plus $\mathrm{I}_{3}-$ ion, and the $\mathrm{I}_{3}$ - was titrated with thiosulfate, $\mathrm{S}_{2} \mathrm{O}_{3}^{2-}$ . The titration required 10.49 $\mathrm{mL}$ of 0.100 $\mathrm{M} \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}$ for complete reaction. What is the mass percent copper in the sample? The balanced equations are
$$2 \mathrm{Cu}^{2+}(a q)+5 \mathrm{I}^{-}(a q) \longrightarrow 2 \mathrm{CuI}(s)+\mathrm{I}_{3}^{-}(a q)$$
$$\mathrm{I}_{3}^{-}(a q)+2 \mathrm{S}_{2} \mathrm{O}_{3}^{2-}(a q) \longrightarrow 3 \mathrm{I}^{-(a q)}+\mathrm{S}_{4} \mathrm{O}_{6}^{2-(a q)}$$

Ronald Prasad

Numerade Educator

Problem 109

The solubility of an ionic compound can be described quantitatively by a value called the solubility product constant, $K_{\mathrm{sp}} .$ For the general process $\mathrm{A}_{a} \mathrm{B}_{b} \rightleftharpoons a \mathrm{A}^{n+}+b \mathrm{B}^{m-}$ $K_{\mathrm{sp}}=\left[\mathrm{A}^{n+}\right]^{a}\left[\mathrm{B}^{m-}\right]^{b} .$ The brackets refer to concentrations in moles per liter.
(a) Write the expression for the solubility product constant of $\mathrm{Ag}_{2} \mathrm{CrO}_{4}$ .
(b) If $K_{\text { sp }}=1.1 \times 10^{-12}$ for $A g_{2} \mathrm{CrO}_{4},$ what are the molar concentrations of $A g^{+}$ and $C r O_{4}^{2-}$ in a saturated solution?

Ronald Prasad

Numerade Educator

Problem 110

Write the expression for the solubility product constant of $\mathrm{MgF}_{2}(\text { see Problem } 4.109) .$ If $\left[\mathrm{Mg}^{2+}\right]=2.6 \times 10^{-4} \mathrm{mol} / \mathrm{L}$ in a saturated solution, what is the value of $K_{\mathrm{sp}} ?$

Ronald Prasad

Numerade Educator

Problem 111

Succinic acid, an intermediate in the metabolism of food molecules, has molecular mass $=118.1$ amu. When 1.926 $\mathrm{g}$ of succinic acid was dissolved in water and titrated, 65.20 $\mathrm{mL}$ of 0.5000 $\mathrm{M} \mathrm{NaOH}$ solution was required to neu- tralize the acid. How many acidic hydrogens are there in a molecule of succinic acid?

Ronald Prasad

Numerade Educator

Problem 112

How could you use a precipitation reaction to separate each of the following pairs of cations? Write the formula for each reactant you would add, and write a balanced net ionic equation for each reaction.
(a) $\mathrm{K}^{+}$ and $\mathrm{Hg}_{2}^{2+} \quad$ (b) $\mathrm{Pb}^{2+}$ and $\mathrm{Ni}^{2+}$
(c) $\mathrm{Ca}^{2+}$ and $\mathrm{NH}_{4}^{+} \quad$ (d) $\mathrm{Fe}^{2+}$ and $\mathrm{Ba}^{2+}$

Ronald Prasad

Numerade Educator

Problem 113

How could you use a precipitation reaction to separate each of the following pairs of anions? Write the formula for each reactant you would add, and write a balanced net ionic equation for each reaction.
(a) $\mathrm{Cl}^{-}$ and $\mathrm{NO}_{3}^{-} \quad$ (b) $\mathrm{S}^{2-}$ and $\mathrm{SO}_{4}^{2-}$
(c) $\mathrm{SO}_{4}^{2-}$ and $\mathrm{CO}_{3}^{2-} \quad$ (d) $\mathrm{OH}^{-}$ and $\mathrm{ClO}_{4}^{-}$

Ronald Prasad

Numerade Educator

Problem 114

Write a balanced net ionic equation for each of the following reactions:
(a) $\mathrm{Mn}(\mathrm{OH})_{2}(s)+\mathrm{H}_{2} \mathrm{O}_{2}(a q) \stackrel{\mathrm{Base}}{\longrightarrow} \mathrm{Mn}(\mathrm{OH})_{3}(s)$
(b) $\mathrm{MnO}_{4}^{2-}(a q) \stackrel{\mathrm{Adid}}{\longrightarrow} \mathrm{MnO}_{2}(s)+\mathrm{MnO}_{4}^{-}(a q)$
(c) $\mathrm{IO}_{3}^{-}(a q)+\mathrm{I}^{-}(a q) \stackrel{\text { Acid }}{\longrightarrow} \mathrm{I}_{3}^{-}(a q)$
(d) $\mathrm{P}(s)+\mathrm{PO}_{4}^{3-}(a q) \stackrel{\mathrm{Base}}{\longrightarrow} \mathrm{HPO}_{3}^{2-}(a q)$

Ronald Prasad

Numerade Educator

Problem 115

A 100.0 mL solution containing aqueous HCl and HBr was titrated with 0.1235 $\mathrm{M} \mathrm{NaOH}$ . The volume of base required to neutralize the acid was 47.14 $\mathrm{mL}$ . Aqueous AgNO $_{3}$ was then added to precipitate the $\mathrm{Cl}^{-}$ and $\mathrm{Br}^{-}$ ions as AgCl and AgBr. The mass of the silver halides obtained was 0.9974 . What are the molarities of the HCl and HBr in the original solution?

Lottie Adams

Numerade Educator

Problem 116

Write balanced net ionic equations for the following reactions in acidic solution:
(a) $\mathrm{S}_{4} \mathrm{O}_{6}^{2-}(a q)+\mathrm{Al}(s) \longrightarrow \mathrm{H}_{2} \mathrm{S}(a q)+\mathrm{A}^{3+}(a q)$
(b) $\mathrm{S}_{2} \mathrm{O}_{3}^{2-}(a q)+\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q) \longrightarrow \mathrm{S}_{4} \mathrm{O}_{6}^{2-}(a q)+\mathrm{Cr}^{3+}(a q)$
(c) $\operatorname{ClO}_{3}^{-}(a q)+\operatorname{As}_{2} S_{3}(s) \longrightarrow_{\mathrm{Cl}^{-}(a q)+\mathrm{H}_{2} \mathrm{AsO}_{4}^{-}(a q)+\mathrm{HSO}_{4}^{-}(a q)}$
(d) $\mathrm{IO}_{3}^{-}(a q)+\operatorname{Re}(s) \longrightarrow \operatorname{ReO}_{4}^{-}(a q)+\mathrm{I}^{-}(a q)$
(e) $\mathrm{HSO}_{4}^{-}(a q)+\mathrm{As}_{4}(s)+\mathrm{Pb}_{3} \mathrm{O}_{4}(s) \rightarrow _{\mathrm{PbSO}_{4}(s)+\mathrm{H}_{2} \mathrm{AsO}_{4}^{-}(a q)}$
(f) $\mathrm{HNO}_{2}(a q) \longrightarrow \mathrm{NO}_{3}^{-}(a q)+\mathrm{NO}(g)$

Vishal Sharma

Numerade Educator

Problem 117

Write balanced net ionic equations for the following reactions in basic solution:
(a) $C_{4} \mathrm{H}_{4} \mathrm{O}_{6}^{2-}(a q)+\mathrm{ClO}_{3}(a q) \longrightarrow \mathrm{CO}_{3}^{2-}(a q)+\mathrm{Cl}^{-}(a q)$
(b) All $(s)+\operatorname{Bi} \mathrm{ONO}_{3}(s) \longrightarrow_{\mathrm{Bi}(s)+\mathrm{NH}_{3}(a q)+\mathrm{Al}(\mathrm{OH})_{4}^{-}(a q)}$
(c) $\mathrm{H}_{2} \mathrm{O}_{2}(a q)+\mathrm{Cl}_{2} \mathrm{O}_{7}(a q) \longrightarrow \mathrm{ClO}_{2}^{-(a q)}+\mathrm{O}_{2}(g)$
(d) $\mathrm{Tl}_{2} \mathrm{O}_{3}(\mathrm{s})+\mathrm{NH}_{2} \mathrm{OH}(a q) \longrightarrow \mathrm{T} \mathrm{OH}(s)+\mathrm{N}_{2}(g)$
(e) $\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}^{2+}(a q)+\mathrm{S}_{2} \mathrm{O}_{4}^{2-}(a q) \longrightarrow_{\mathrm{SO}_{3}^{2-}(a q)+\mathrm{Cu}(s)+\mathrm{NH}_{3}(a q)}$
(f) $\operatorname{Mn}(\mathrm{OH})_{2}(s)+\mathrm{MnO}_{4}^{-}(a q) \longrightarrow \mathrm{MnO}_{2}(s)$

Lottie Adams

Numerade Educator

Problem 118

A mixture of CuO and $\mathrm{Cu}_{2} \mathrm{O}$ with a mass of 10.50 $\mathrm{g}$ is reduced to give 8.66 $\mathrm{g}$ of pure Cu metal. What are the amounts in grams of $\mathrm{CuO}$ and $\mathrm{Cu}_{2} \mathrm{O}$ in the original mixture?

Ronald Prasad

Numerade Educator

Problem 119

When 75.0 $\mathrm{mL}$ of a 0.100 $\mathrm{M}$ lead(Il) nitrate solution is mixed with 100.0 $\mathrm{mL}$ of a 0.190 $\mathrm{M}$ potassium iodide solution, a yellow-orange precipitate of lead(II) iodide is formed.
(a) What mass in grams of lead(II) iodide is formed, assuming the reaction goes to completion?
(b) What is the molarity of each of the ions $\mathrm{Pb}^{2+}, \mathrm{K}^{+}, \mathrm{NO}_{3}$ , and $\mathrm{I}^{-}$ in the resulting solution?

Lottie Adams

Numerade Educator

Problem 120

A sample of metal (M) reacted with both steam and aqueous $\mathrm{HCl}$ to release $\mathrm{H}_{2},$ but did not react with water at room temperature. When 1.000 $\mathrm{g}$ of the metal was burned in oxygen it formed 1.890 $\mathrm{g}$ of a metal oxide, $\mathrm{M}_{2} \mathrm{O}_{3} .$ What is the identity of the metal?

Ronald Prasad

Numerade Educator

Problem 121

An unknown metal (M) was found not to react with either water or steam, but its reactivity with aqueous acid was not investigated. When a 1.000 g sample of the metal was burned in oxygen and the resulting metal oxide converted to a metal sulfide, 1.504 g of sulfide was obtained. What is the identity of the metal?

Ronald Prasad

Numerade Educator

Problem 122

Hydrogen peroxide can be either an oxidizing or reducing agent depending on the circumstances. Write balanced net ionic equations for each of the following reactions, and determine in each case whether hydrogen peroxide is oxidized (acts as a reducing agent) or reduced (acts as an oxidizing agent).
(a) $\mathrm{HCl}(a q)+\mathrm{H}_{2} \mathrm{O}_{2}(a q) \longrightarrow \mathrm{Cl}_{2}(a q)+\mathrm{H}_{2} \mathrm{O}(l)$
(b) (acidic) $\mathrm{MnO}_{4}^{-}(a q)+\mathrm{H}_{2} \mathrm{O}_{2}(a q) \longrightarrow \mathrm{Mn}^{2+}(a q)+\mathrm{O}_{2}(g)$
(c) $\mathrm{H}_{2} \mathrm{O}_{2}(a q)+\mathrm{Cl}_{2}(a q) \longrightarrow \mathrm{HCl}(a q)+\mathrm{O}_{2}(g)$

Ronald Prasad

Numerade Educator

Problem 123

A mixture of acetic acid $\left(\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H} ; \text { monoprotic) and }\right.$ oxalic acid $\left(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4} ; \text { diprotic ) requires } 27.15 \mathrm{mL} \text { of } 0.100 \mathrm{M}\right.$ $\mathrm{NaOH}$ to neutralize it. When an identical amount of the mixture is titrated, 15.05 $\mathrm{mL}$ of 0.0247 $\mathrm{M} \mathrm{KM} \mathrm{nO}_{4}$ is needed for complete reaction. What is the mass percent of each acid in the mixture? (Acetic acid does not react with $\mathrm{MnO}_{4}^{-}$ . The equation for the reaction of oxalic acid with $\mathrm{MnO}_{4}^{-}$ was given in Problem 4.101 .)

Lottie Adams

Numerade Educator

Problem 124

Iron content in ores can be determined by a redox procedure in which the sample is first reduced with $\mathrm{Sn}^{2+},$ as in Problem $4.98,$ and then titrated with $\mathrm{KMnO}_{4}$ to oxidize the $\mathrm{Fe}^{2+}$ to $\mathrm{Fe}^{3+} .$ The balanced equation is
$$\begin{aligned} \mathrm{MnO}_{4}^{-}(a q)+5 \mathrm{Fe}^{2+}(a q)+& 8 \mathrm{H}^{+}(a q) \longrightarrow \\ & \mathrm{Mn}^{2+}(a q)+5 \mathrm{Fe}^{3+}(a q)+4 \mathrm{H}_{2} \mathrm{O}(l) \end{aligned}$$
What is the mass percent Fe in a 2.368 g sample if 48.39 $\mathrm{mL}$ of a 0.1116 $\mathrm{M} \mathrm{KMnO}_{4}$ solution is needed to titrate the Fe $^{3+} ?$

Ronald Prasad

Numerade Educator

Problem 125

A mixture of $\mathrm{FeCl}_{2}$ and $\mathrm{NaCl}$ is dissolved in water, and addition of aqueous silver nitrate then yields 7.0149 $\mathrm{g}$ of a precipitate. When an identical amount of the mixture is titrated with $\mathrm{MnO}_{4}^{-}, 14.28 \mathrm{mL}$ of 0.198 $\mathrm{M} \mathrm{KMnO}_{4}$ is needed for complete reaction. What are the mass percents of the two compounds in the mixture? $\mathrm{Na}^{+}$' and $\mathrm{Cl}^{-}$ do not react with $\mathrm{MnO}_{4}^{-}$. The equation for the reaction of $\mathrm{Fe}^{2+}$ with $\mathrm{MnO}_{4}^{-}$ was given in Problem $4.124 .$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 126

Assume that you dissolve 10.0 $\mathrm{g}$ of a mixture of NaOH and $\mathrm{Ba (\mathrm{OH})_{2}$ in 250.0 $\mathrm{mL}$ of water and titrate with 1.50 $\mathrm{M}$ hydrochloric acid. The titration is complete after 108.9 $\mathrm{mL}$ of the acid has been added. What is the mass in grams of each substance in the mixture?

Lottie Adams

Numerade Educator

Problem 127

The following three solutions are mixed: 100.0 $\mathrm{mL}$ of $0.100 \mathrm{M} \mathrm{Na}_{2} \mathrm{SO}_{4}, 50.0 \mathrm{mL}$ of $0.300 \mathrm{M} \mathrm{ZnCl}_{2},$ and 100.0 $\mathrm{mL}$ of 0.200 $\mathrm{M} \mathrm{Ba}(\mathrm{CN})_{2}$
(a) What ionic compounds will precipitate out of solution?
(b) What is the molarity of each ion remaining in the solution assuming complete precipitation of all insoluble compounds?

Ronald Prasad

Numerade Educator

Problem 128

A 250.0 g sample of a white solid is known to be a mixture of KNO $_{3}, \mathrm{BaCl}_{2},$ and $\mathrm{NaCl}$ . When 100.0 $\mathrm{g}$ of this mixture is dissolved in water and allowed to react with excess $\mathrm{H}_{2} \mathrm{SO}_{4}$ 67.3 $\mathrm{g}$ of a white precipitate is collected. When the remaining 150.0 g of the mixture is dissolved in water and allowed to react with excess AgNO $_{3}, 197.6 \mathrm{g}$ of a second precipitate is collected.
(a) What are the formulas of the two precipitates?
(b) What is the mass of each substance in the original 250 g mixture?

Lottie Adams

Numerade Educator

Problem 129

Four solutions are prepared and mixed in the following order:
(1) Start with 100.0 $\mathrm{mL}$ of 0.100 $\mathrm{M} \mathrm{BaCl}_{2}$
(2) Add 50.0 $\mathrm{mL}$ of 0.100 $\mathrm{M} \mathrm{AgNO}_{3}$
(3) Add 50.0 $\mathrm{mL}$ of 0.100 $\mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}$
(4) Add 250.0 $\mathrm{mL}$ of 0.100 $\mathrm{M} \mathrm{NH}_{3}$
Write an equation for any reaction that occurs after each step, and calculate the concentrations of $\mathrm{Ba}^{2+}, \mathrm{Cl}^{-}, \mathrm{NO}_{3}^{-}$ $\mathrm{NH}_{3},$ and $\mathrm{NH}_{4}^{+}$ in the final solution, assuming that all reactions go to completion.

Lottie Adams

Numerade Educator

Problem 130

To 100.0 mL of a solution that contains 0.120 $\mathrm{M} \operatorname{Cr}\left(\mathrm{NO}_{3}\right)_{2}$ and 0.500 $\mathrm{M} \mathrm{HNO}_{3}$ is added 20.0 $\mathrm{mL}$ of 0.250 $\mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ The dichromate and chromium(II) ions react to give chromium(III) ions.
(a) Write a balanced net ionic equation for the reaction.
(b) Calculate the concentrations of all ions in the solution after reaction. Check your concentrations to make sure that the solution is electrically neutral.

Lottie Adams

Numerade Educator

Problem 131

Sodium nitrite, NaNO $_{2},$ is frequently added to processed meats as a preservative. The amount of nitrite ion in a sample can be determined by acidifying to form nitrous acid $\left(\mathrm{HNO}_{2}\right),$ letting the nitrous acid react with an excess of iodide ion, and then titrating the $\mathrm{I}_{3}^{-}$ ion that results with thiosulfate solution in the presence of a starch indicator. The unbalanced equations are
$$\text { (1) } \mathrm{HNO}_{2}+\mathrm{I}^{-} \longrightarrow \mathrm{NO}+\mathrm{I}_{3}^{-} \text { (in acidic solution) }$$
$$\text { (2) } \mathrm{I}_{3}^{-}+\mathrm{S}_{2} \mathrm{O}_{3}^{2-} \longrightarrow \mathrm{I}^{-}+\mathrm{S}_{4} \mathrm{O}_{6}^{2-}$$
(a) Balance the two redox equations.
(b) When a nitrite-containing sample with a mass of 2.935 g was analyzed, 18.77 $\mathrm{mL}$ of 0.1500 $\mathrm{M} \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}$ solution was needed for the reaction. What is the mass percent of $\mathrm{NO}_{2}^{-}$ ion in the sample?

Ronald Prasad

Numerade Educator

Problem 132

Brass is an approximately alloy of copper and zinc, along with small amounts of tin, lead, and iron. The mass percents of copper and zinc can be determined by a proce dure that begins with dissolving the brass in hot nitric acid. The resulting solution of $\mathrm{Cu}^{2+}$ and $\mathrm{Zn}^{2+}$ ions is then treated with aqueous ammonia to lower its acidity, followed by addition of sodium thiocyanate (NaSCN) and sulfurous $\mathrm{acid}\left(\mathrm{H}_{2} \mathrm{SO}_{3}\right)$ to precipitate copper(1) thiocyanate (CuSCN). The solid CuSCN is collected, dissolved in aqueous acid, and treated with potassium iodate (KIO $_{3} )$ to give iodine, which is then titrated with aqueous sodium thiosulfate $\left(\mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3}\right)$ . The filtrate remaining after $\mathrm{CuSCN}$ has been removed is neutralized by addition of aqueous ammonia, and a solution of diammonium hydrogen phosphate $\left[\left(\mathrm{NH}_{4}\right)_{2} \mathrm{HPO}_{4}\right]$ is added to yield a precipitate of zinc ammonium phosphate (ZnNH $\mathrm{PO}_{4} ) .$ Heating the precipitate to $900^{\circ} \mathrm{C}$ converts it to zinc pyrophosphate $\left(\mathrm{Zn}_{2} \mathrm{P}_{2} \mathrm{O}_{7}\right),$ which is weighed. The equations are
(1) $\mathrm{Cu}(s)+\mathrm{NO}_{3}^{-}(a q) \longrightarrow \mathrm{Cu}^{2+}(a q)+\mathrm{NO}(g)(\text { in acid })$
(2) $\mathrm{Cu}^{2+}(a q)+\mathrm{SCN}^{-}(a q)+\mathrm{HSO}_{3}^{-}(a q) \longrightarrow_{\mathrm{CuSCN}(s)+\mathrm{HSO}_{4}^{-(a q)}(\text { in acid })}$
(3) $\mathrm{Cu}^{+}(a q)+\mathrm{IO}_{3}^{-}(a q) \longrightarrow \mathrm{Cu}^{2+}(a q)+\mathrm{I}_{2}(a q)(\text { in acid })$
(4) $\mathrm{I}_{2}(a q)+\mathrm{S}_{2} \mathrm{O}_{3}^{2-}(a q) \longrightarrow \mathrm{I}^{-}(a q)+\mathrm{S}_{4} \mathrm{O}_{6}^{2-}(a q)(\text { in acid })$
(5) $\mathrm{ZnNH}_{4} \mathrm{PO}_{4}(s) \longrightarrow \mathrm{Zn}_{2} \mathrm{P}_{2} \mathrm{O}_{7}(s)+\mathrm{H}_{2} \mathrm{O}(g)+\mathrm{NH}_{3}(g)$
(a) Balance all equations.
(b) When a brass sample with a mass of 0.544 g was subjected to the preceding analysis, 10.82 $\mathrm{mL}$ of 0.1220 $\mathrm{M}$ sodium thiosulfate was required for the reaction with iodine. What is the mass percent copper in the brass?
(c) The brass sample in part (b) yielded 0.246 $\mathrm{g}$ of $\mathrm{Zn}_{2} \mathrm{P}_{2} \mathrm{O}_{7}$ What is the mass percent zinc in the brass?

Lottie Adams

Numerade Educator

Problem 133

A certain metal sulfide, $\mathrm{MS}_{n}$ (where $n$ is a small integer), is widely used as a high-temperature lubricant. The substance is prepared by reaction of the metal pentachloride $\left(\mathrm{MCl}_{5}\right)$ with sodium sulfide $\left(\mathrm{Na}_{2} \mathrm{S}\right)$ . Heating the metal sulfide to $700^{\circ} \mathrm{C}$ in air gives the metal trioxide $\left(\mathrm{MO}_{3}\right)$ and sulfur dioxide $\left(\mathrm{SO}_{2}\right),$ which reacts with $\mathrm{Fe}^{3+}$ ion under aqueous acidic conditions to give sulfate ion $\left(\mathrm{SO}_{4}^{2-}\right) .$ Addition of aqueous $\mathrm{BaCl}_{2}$ then forms a precipitate of $\mathrm{BaSO}_{4}$ The unbalanced equations are:
(1) $\mathrm{MCl}_{5}(s)+\mathrm{Na}_{2} \mathrm{S}(s) \longrightarrow \mathrm{MS}_{n}(s)+\mathrm{S}(l)+\mathrm{NaCl}(s)$
(2) $\mathrm{MS}_{n}(s)+\mathrm{O}_{2}(g) \longrightarrow \mathrm{MO}_{3}(s)+\mathrm{SO}_{2}(g)$
(3) $\mathrm{SO}_{2}(g)+\mathrm{Fe}^{3+}(a q) \longrightarrow \mathrm{Fe}^{2+}(a q)+\mathrm{SO}_{4}^{2-}(a q)(\text { in acid })$
(4) $\mathrm{SO}_{4}^{2-}(a q)+\mathrm{Ba}^{2+}(a q) \longrightarrow \mathrm{BaSO}_{4}(s)$
Assume that you begin with 4.61 $\mathrm{g}$ of MCl_ and that reaction $(1)$ proceeds in 91.3$\%$ yield. After oxidation of the MS, product, oxidation of $\mathrm{SO}_{2},$ and precipitation of sulfate ion, 7.19 $\mathrm{g}$ of $\mathrm{BaSO}_{4}(s)$ is obtained.
(a) How many moles of sulfur are present in the MS, sample?
(b) Assuming several possible values for $n(n=1,2,3$ $\ldots$ ), what is the atomic mass of $\mathrm{M}$ in each case?
(c) What is the likely identity of the metal $M,$ and what is the formula of the metal sulfide MS $_{n} ?$
(d) Balance all equations.

Lottie Adams

Numerade Educator

Problem 134

On heating a 0.200 g sample of a certain semimetal in air, the corresponding oxide $\mathrm{M}_{2} \mathrm{O}_{3}$ was obtained. When the oxide was dissolved in aqueous acid and titrated with $\mathrm{KMnO}_{4}, 10.7 \mathrm{mL}$ of $0.100 \mathrm{M} \mathrm{MnO}_{4}-$ was required for complete reaction. The unbalanced equation is
$$\mathrm{H}_{3} \mathrm{MO}_{3}(a q)+\mathrm{MnO}_{4}^{-}(a q) \longrightarrow_{\mathrm{H}_{3} \mathrm{MO}_{4}(a q)+\mathrm{Mn}^{2+}(\text { in acid })}$$
(a) Balance the equation.
(b) How many moles of oxide were formed, and how many moles of semimetal were in the initial 0.200 g sample?
(c) What is the identity of the semimetal M?

Ronald Prasad

Numerade Educator