Exam Prep Worksheet

1011ExamPrepWorksheet.doc

Chapter 19.1 Balancing Redox Equations Chapter 19.1 Multiple Choice 1) What is the oxidation number of phosphorus in (NH4)H3P2O7?

a) +7 b) +6 c) +5 d) +4 e) +3

Chapter 19.1 Longer answer 1) Balance the following redox reaction in basic solution.

SO42−(aq) + I−(aq) → I2(aq) + H2S(aq)

2) Consider the following reaction:

As2O3 (s) + MnO4- (aq) → H3AsO4 (aq) + Mn2+ (aq)

a) Identify the oxidation number of As in As2O3.

b) Which species is being reduced?

c) Balance the above reaction in acidic solution.

3) Balance the following redox skeleton equation in basic solution:

Fe2+ (aq) + Cr2O72- (aq) → Fe3+ (aq) + Cr3+ (aq)

Chapter 9 Ionic and Covalent Bonding Chapter 9 Multiple Choice 1) The nitrogen–hydrogen bond in a molecule of ammonia is an example of what

type of bond?

a) ionic bond b) non-polar covalent bond c) polar covalent bond

d) hydrogen bond e) none of the above

2) A triple bond is generally composed of

a) three π bonds b) two π bonds and one σ bond

c) one π bond and two σ bonds d) three σ bonds

e) none of the above describes a triple bond.

3) Xenon atoms in a compound like XeF4 can be shown to have sp3d2 hybrid

orbitals. How many of these sp3d2 hybrid orbitals are there associated with Xe?

a) 2 b) 4 c) 6 d) 8

Chapter 10 Molecular Geometry Chapter 10 Multiple Choice 1) Which of the following statements is FALSE for sp3 hybridized orbitals?

a) They are formed from the combination of one s orbital and three p orbitals.

b) There are four sp3 orbitals.

c) When an element has sp3 hybridization it can form 4 single bonds with

other atoms.

d) The angle between bonds in a molecule whose central atom has sp3

hybridization is 90o.

e) sp3 hybridization gives water its bent geometry

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Chapter 10 Shorter Answer 1) The molecule methyl cyanoacrylate, shown below, is used to make polymers.

Specify the type of hybridization of the carbon atoms labeled X, Y and Z.

H2C C

C

N

O

OCH3

ZX

Y

2) Write the two electron-dot resonance structures for the molecule SeO2.

3) What is the hybridization of N in the molecule F-N=N-F?

4) Briefly, but completely, explain or define hybrid orbitals.

Chapter 11 States of Matter Chapter 11 Multiple choice 1) Which of the following is a covalent network solid?

a) Diamond b) Calcium c) Calcium chloride

d) Iodine e) Sucrose

2) Krypton has a higher melting point than argon because it has

a) Hydrogen bonding b) Ionic bonds

c) A permanent dipole moment d) Stronger dispersion forces

e) A greater ionization energy

3) Which statement is most true about an ionic solid?

a) It is soft and has a low melting point.

b) It is hard and has a low melting point.

c) It is soft and has a high melting point.

d) It is hard and has a high melting point.

4) A crystalline solid of unknown origin melts to form a liquid that conducts an

electrical current. The solid also has a high melting point and shatters when

struck by a hammer. The solid is most likely to be

a) an ionic solid. b) a covalent network sold.

c) a molecular solid. d) a metallic solid.

5) Which of the intermolecular forces is the most important contributor to the high

melting point of water?

a) dipole-dipole forces b) dispersion forces

c) hydrogen bonding d) ion-dipole forces

6) In which substance would the London dispersion forces be weakest?

a) Ne b) Ar c) Kr d) Xe

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7) Which of the listed intermolecular forces is most likely to be the strongest?

a) dipole-dipole forces

b) hydrogen bonds

c) London dispersion forces

d) all three listed forces will have relatively the same strength

8) Of the following four molecules, which molecules would we expect to be polar?

CF4 PF3 H2O HF

a) All of these molecules are polar.

b) All of the molecules are polar except for CF4.

c) Only PF3 and H2O are polar.

d) None of these molecules are polar.

Chapter 11 Shorter Answer 1) The strongest intermolecular force that occurs between two NH3 molecules is

(ion-dipole, dipole-dipole, London dispersion, hydrogen bonding). Choose the

correct phrase in brackets and briefly explain your answer.

2) What is the difference between dipole-dipole forces and London dispersion

forces?

3) Identify the likely kind of intermolecular forces present in each of the following:

methanol, CH3OH

hydrogen chloride, HCl

chloromethane, CH3Cl

oxygen, O2

4) Place the following compounds, methyl alcohol, CH3OH, oxygen, O2, and

hydrogen chloride, HCl, in order of increasing melting point.

5) Draw three possible Lewis dot structures for OCN-. Be sure to show the formal

charges for each structure. Circle the best possible Lewis dot structure of the

three.

6) Define molecular solid.

7) Briefly, but completely, explain or define covalent network solid.

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Chapter 11 Longer Answer 1) Complete the following table:

Species

OF2

PBr5

IF4

−

Lewis electron dot structure

Sketch of the 3- dimensional

shape

Name of the

molecular shape

Approximate bond angles

2) Below is a list of four molecules.

a) For each molecule list ALL possible intermolecular forces that occur between

two of the same molecules.

H2S [34 g·mol-1] CH3OH [32 g·mol-1]

C2H6 [30 g·mol-1] Ne [20 g·mol-1]

b) Based on your answers in part a), rank the molecules in order of lowest boiling

point to highest boiling point.

c) Draw the Lewis dot structure for H2S and name both the electron distribution

shape and the molecular geometry.

Chapter 13 Rates of Reaction Chapter 13 Multiple choice 1) What are the units of the rate constant for the following rate law?

Rate = k[A]2[B]1[C]0

a) L ⋅mol ⋅s2 -2 -1 b) L⋅mol-1⋅s-1 c) L2⋅mol-2⋅s-2

d) L3⋅mol-3⋅s-1 e) mol3⋅L-3⋅s-1

2) The rate of a reaction is measured in mol⋅L-1⋅s-1. What are the units for the rate

constant if this reaction is a termolecular reaction?

a) s-1 b) mol2⋅L-2⋅s-1 c) L⋅mol-1⋅s-1

d) L2⋅mol-2⋅s-2 e) L2⋅mol-2⋅s-2

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3) For a reaction that follows the rate law, rate = k[A][B]2, what will happen to the

rate of reaction if the concentration of A is increased by a factor of three and the

concentration of B is increased by a factor of 2?

a) increases by a factor of 3 b) increases by a factor of 4

c) increases by a factor of 6 d) increases by a factor of 12

4) The rate law for the reaction: 2 NO2 + O3 → N2O5 + O2 is rate = k[NO2][O3].

Which of the following mechanisms is consistent with this rate law?

a) 2 NO2 → N2O4 fast

N2O4 + O3 → N2O5 + O2 slow

b) NO2 + O3 → NO5 fast

2 NO5 → N2O5 + 5/2 O2 slow

c) NO2 + O3→ NO3 + O2 slow

NO3 + NO2 → N2O5 fast

d) 2 NO2→ N2O2 + O2 slow

N2O2 + O3 → N2O5 fast

5) The units for a first order rate constant are:

a) mol⋅L-1⋅s-1 b) L⋅mol-1⋅s-1 c) s-1 d) L2⋅mol-2⋅s-1

6) Ozone decomposes to oxygen according to the equation: 2 O3(g) → 3 O2(g). If

the rate at which O2 appears is 6.0 x 10-5 mol⋅s-1 at a particular instant, what is

the-rate of disappearance of O3 at the same instant?

a) 6.0 x 10-5 mol/s b) 4.0 x 10-5 mol⋅s-1 c) 9.0 x 10-5 mol⋅s-1

d) 12 x10-5 mol⋅s-1

7) Which of the following statements about a catalyst are true?

a) A catalyst changes the position of equilibrium in a reaction

b) a catalyst increases the temperature of a reaction

c) a catalyst is consumed in a chemical reaction

d) a catalyst provides a lower energy pathway for a reaction

8) What factor affects the rate of a chemical reaction?

a) activation energy b) net energy c) potential energy d) rate limiting energy

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9) Which of the following four statements are TRUE about reaction mechanisms?

I ) A rate law can be written from the molecularity of the slowest

elementary step

II ) A final rate law can include intermediates

III) The rate of reaction is dependent on the fastest step in the mechanism

IV) A mechanism can never be proven to be the correct pathway for a

reaction

a) I, II, III b) II, IV c) I, III d) I, IV

10) The decomposition of dinitrogen pentaoxide is described by the chemical

equation: 2 N2O5 (g) → 4 NO (g) + O2 (g). If the rate of appearance of O2 is

1.20 mol⋅L-1⋅min-1 at a particular moment, what is the rate of disappearance of

N2O5 at that same moment?

a) 4.80 mol⋅L-1⋅min-1 b) 1.20 mol⋅L-1⋅min-1 c) 2.40 mol⋅L-1⋅min-1

d) -1.20 mol⋅L-1⋅min-1

11) “Instantaneous rate” is defined as the

a) change in concentration per unit time

b) equation showing how the rate depends on the concentration of each reactant

c) rate of reaction at a particular time

d) rate of reaction during a particular time interval

12) What factor affects the rate of a chemical reaction?

a) collision frequency

b) fraction of molecules with sufficient energy

c) orientation of molecules in the collision

d) all of the above

13) The decomposition of ozone in the stratosphere can occur by the following two-

step mechanism:

Br + O3 → BrO + O2

BrO + O → Br + O2

Which statement is true for the mechanism?

a) BrO is a catalyst; Br is a reaction intermediate.

b) BrO is a reaction intermediate; Br is a reaction intermediate.

c) BrO is a reaction intermediate; Br is a catalyst.

d) BrO is a catalyst; Br is a catalyst.

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14) The pre-exponential factor, A, in the Arrhenius equation, k = A e-(Ea/RT), can be

broken down into the:

a) collision frequency z and the fraction of collisions of sufficient energy f. b) steric factor p and the fraction of collisions of sufficient energy f. c) collision frequency z and the steric factor p.

d) collision frequency z, the steric factor p, and the fraction of collisions of

sufficient energy f. 15) A given reaction forms A as a product. If in the time interval between 300

seconds and 400 seconds ∆[A] / ∆ t = 3.7 x 10-5 mol⋅L-1⋅s-1, then which statement

is most true for the time interval between 700 and 800 seconds?

a) ∆[A] / ∆ t < 3.7 x 10-5 mol⋅L-1⋅s-1

b) ∆[A] / ∆ t = 3.7 x 10-5 mol⋅L-1⋅s-1

c) ∆[A] / ∆ t > 3.7 x 10-5 mol⋅L-1⋅s-1

d) ∆[A] / ∆ t = 0.0 mol⋅L-1⋅s-1

16) Which statement is true about the orders of a reaction?

a) The order with respect to a given reactant is always the same as the

stoichiometric coefficient in the balanced equation.

b) The overall order of the reaction can be found by multiplying the orders with

respect to each reactant.

c) The orders with respect to the reactants must be determined experimentally.

d) The orders must be positive integers.

17) Increasing the temperature of a chemical reaction by ten degrees Celcius

approximately doubles the rate of the reaction. This is primarily because:

a) more collisions occur with sufficient energy to reach the transition state.

b) the number of collisions between molecules doubles.

c) the activation energy increases.

d) the activation energy decreases.

18) Which statement is most true about reaction intermediates and catalysts?

a) Both are consumed in an early elementary step and are reformed in a later

elementary step.

b) Both are formed in an early elementary step and are consumed in a later

elementary step.

c) Catalysts are formed in early elementary steps and are consumed in later steps.

Reaction intermediates are consumed in early steps and are reformed in later

steps.

d) Reaction intermediates are formed in early elementary steps and are consumed

in later steps. Catalysts are consumed in early steps and are reformed in later

steps.

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19) A mechanism for a naturally occurring reaction that destroys ozone is

Step 1: O3 (g) + HO (g) → HO2 (g) + O2 (g)

Step 2: HO2 (g) + O (g) → HO (g) + O2 (g)

Which species is a catalyst and what type of catalysis is occurring?

a) HO, homogeneous b) HO, heterogeneous

c) HO2, homogeneous d) HO2, heterogeneous

20) Which of the following things can be done to guarantee an increase in the rate of

a reaction?

a) increasing the temperature.

b) increasing the concentration of a reactant.

c) neither a) or b) will guarantee an increase in the rate of a reaction.

d) both a) and b) will guarantee an increase in the rate of a reaction.

21) Which of the following statements would be correct regarding the following

reaction?

2 H2 (g) + O2 (g) → 2 H2O (g)

a) The rate of H2 disappearance is twice the rate of O2 disappearance.

b) The rate of H2O appearance is equal to the rate of O2 disappearance.

c) The rate of H2O disappearance is twice the rate of O2 appearance.

d) The rate of O2 disappearance is twice the rate of H2 disappearance.

22) The reaction

H2O2 (aq) + 3 I- (aq) + 2 H+ (aq) → 2 H2O (l) + I3- (aq)

has an observed rate law

rate = k [H2O2] [I-] [H+]

A mechanism is proposed for the overall reaction. Which elementary reaction

below could be the rate-determining step of the proposed mechanism?

a) H2O2 (aq) + 3 I- (aq) + 2 H+ (aq) → 2 H2O (l) + I3- (aq)

b) H2O2 (aq) + I- (aq) + 2 H+ (aq) → H2O (l) + OI- (aq)

c) H2O2 (aq) + I- (aq) + H+ (aq) → H2O (l) + HOI (aq)

d) none of these elementary steps can be the rate-determining step

23) According to the collision theory of kinetics, which statement best describes the

rate of a chemical reaction?

a) All collisions result in a chemical reaction.

b) The greater the difference in energy between the reactants and the transition

state, the faster is the reaction.

c) All collisions between molecules with at least a minimum kinetic energy and

the proper orientation result in reaction.

d) All collisions between molecules with at least a minimum kinetic energy result

in reaction.

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24) If we perform a reaction at a higher temperature compared the same reaction at a

lower temperature, which sentence best describes what happens to the rate of

reaction?

a) The reaction at the higher temperature will always have a slower rate.

b) The reaction at the higher temperature will always have a faster rate.

c) The reaction at the higher temperature may or may not have a faster rate.

d) The reaction at the higher temperature will have the same rate.

Chapter 13 Shorter answer 1) Define reaction intermediate.

2) Briefly, but completely, explain or define transition state.

Chapter 13 Problems 1) The rate constant for a particular reaction increased by a factor of 5.00 when the

temperature was raised from 225 to 325K. Calculate the value of the activation

energy in kJ/mol.

2) For the reaction A(g) + B(g) + C(g) → D(g) the following data were obtained:

[A]o [B]o [C]o initial rate mol⋅L-1 mol⋅L-1 mol⋅L-1 mol⋅L-1⋅s-1

1 0.0500 0.0500 0.0100 6.25 x 10-3

2 0.1000 0.0500 0.0100 1.25 x 10-2

3 0.1000 0.1000 0.0100 5.00 x 10-2

4 0.0500 0.0500 0.0200 6.25 x 10-3

Determine the rate law and the value of the rate constant for this reaction.

3) The activation energy for a certain reaction is 113 kJ/mol. By what factor (how

many times) will the rate constant decrease when the temperature is lowered from

325 to 310K?

4) The results of 4 experiments carried out to study the reaction:

A(aq) + 5 B(aq) + 6 C(aq) → 3 D(l) + 3 E(l)

are given in the following table:

[A]o [B]o [C]o initial rate mol⋅L-1 mol⋅L-1 mol⋅L-1 mol⋅L-1⋅s-1

1 0.10 0.10 0.10 8.0 x 10-4

2 0.20 0.10 0.10 1.6 x 10-3

3 0.20 0.20 0.10 3.2 x 10-3

4 0.10 0.10 0.20 3.2 x 10-3

Determine the rate law and the value of the rate constant for this reaction.

5) What fraction of collisions will have sufficient energy to achieve reaction for a

gas phase reaction that has an activation energy of 68 kJ⋅mol-1 at 25 °C?

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6) The aquation of tris(1,10-phenanthroline)iron(II) in acid solution takes place

according to the equation:

Fe(phen)32+ + 3 H3O+ + 3 H2O → Fe(H2O)6

2+ + 3 phenH+

If the activation energy is 126 kJ/mol and the frequency factor is 8.62 x 1017 s-1, at

what temperature is the rate constant equal to 3.63 x 10-3 s-1 for the reaction?

7) A reaction

A + B → C + D

is first order with respect to A and is third order overall.

a) What is the rate law for the reaction?

b) The reaction at 25.0 °C has a rate of 8.52 x 10-2 mol⋅(L⋅s)-1 when the

concentration of A is 2.45 mol⋅L-1 and the concentration of B is 0.583 mol⋅L-1.

What is the rate constant for the reaction at 25.0 °C?

c) If the rate constant for the reaction at 80.0 °C is 2.985 L2⋅mol-2⋅s-1, what is the

activation energy for the reaction in kJ⋅mol-1?

8) For the reaction

C5H11Br (aq) + H2O (l) → C5H10 (aq) + H3O+ (aq) + Br- (aq)

the observed rate law is rate = k [C5H11Br]. A proposed three-step mechanism

for the reaction is

H2O (l) → H2 (g) + ½ O2 (g) slow

C5H11Br (aq) + ½ H2 (g) + O2 (g) → C5H10 (aq) + Br2+ (aq) + 2 OH- (aq) fast

Br2+ (aq) + 2 OH- (aq) + H2 (g) → H3O+ (aq) + Br- (aq) + ½ H2 (g) fast

There are several reasons why this proposed mechanism cannot be right.

Assuming that all the chemicals have been proven to exist (i.e. “Br2+ (aq) does not

exist in real life” is not an acceptable reason) give three of the reasons.

9) The decomposition of HI into hydrogen and iodine:

2 HI (g) → H2 (g) + I2 (g)

has rate constants of 0.0790 L⋅mol-1⋅s-1 and 0.240 L⋅mol-1⋅s-1 respectively at

temperatures of 781.0 K and 813.0 K. What is the activation energy in kJ⋅mol-1

for the reaction?

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10) For the reaction

2 NO2Cl (g) → 2 NO2 + Cl2 (g)

the observed rate law is rate = k [NO2Cl].

Two mechanisms for the reaction are proposed below. In the box below each

mechanism, identify any reaction intermediates and catalysts in the given

mechanism and briefly explain whether or not the mechanism is plausible.

Mechanism 1

Step 1: NO2Cl → NO2 (g) + Cl (g) slow Step 2: NO2Cl (g) + Cl (g) → NO2 + Cl2 (g) fast Mechanism 2

Step 1: NO2Cl (g) + NO2Cl (g) → NO3Cl (g) + NO (g) + Cl (g) slow Step 2: NO (g) + Cl (g) + O2 (g) → NO3Cl (g) fast Step 3: NO3Cl (g) + NO3Cl (g) → 2 NO2 (g) + Cl2 (g) + O2 (g) fast

11) The following set of initial rate data was obtained for the reaction:

BrO3- (aq) + 5 Br- (aq) + 6 H+ (aq) → 3 Br2 (aq) + 3 H2O (l)

[BrO3

-] mol·L-1

[Br -] mol·L-1

[H+] mol·L-1

initial rate mol·L-1·s-1

0.10 0.10 0.10 8.0 x 10-4

0.20 0.10 0.10 1.6 x 10-3

0.20 0.15 0.10 2.4 x 10-3

0.10 0.10 0.25 5.0 x 10-3

Determine the rate law and the value of the rate constant.

Chapter 12.7 Osmosis Chapter 12.7 Shorter Answer 1) A solution of an unknown substance in water at 300K gives rise to an osmotic

pressure of 3.85 atm. What is the molarity of the solution?

2) A 25.00 mL aqueous solution containing 0.420 g of hemoglobin has an osmotic

pressure of 4.6 mmHg at 27.0 °C. What is the molar mass of hemoglobin?

3) An aqueous solution with a volume of 100 mL has 0.122 g of an unknown solute

dissolved in it. If the solution has an osmotic pressure of 16.0 mmHg at 21.0 °C,

then what is the molar mass of the solute?

Chapter 14 Chemical Equilibrium Chapter 14 Multiple Choice 1) The value of the equilibrium constant Kp:

a) Changes as the initial concentrations of reactants change

b) Changes as the temperature changes

c) Changes as the pressure changes

d) Changes when a catalyst is added

e) Is never equal to the value of the equilibrium constant Kc

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2) If KC1 is the equilibrium constant for the reaction:

H2SO4(aq) + H2O(l) → H3O+(aq) + HSO4(aq)

and KC2 is the equilibrium constant for the reaction:

HSO4(aq) + H2O(l) → H3O+(aq) + SO42(aq)

what is the equilibrium constant for the overall equilibrium:

H2SO4(aq) + 2 H2O(l) → 2 H3O+(aq) + SO42(aq)

a) KC2 (the slower step) b) KC1 + KC2 c) KC1/KC2

d) KC1 – KC2 e) KC1 x KC2

3) If Kc = 7.04 x 10-2 for the reaction 2 HBr(g) ∏ H2(g) + Br2(g), what is the value

of Kc for the reaction: ½ H2(g) + ½ Br2(g) ∏ HBr(g)?

a) 3.52 x 10-2 b) 0.265 c) 3.77 d) 28.4

4) If Kc is the equilibrium constant for a forward reaction, what is Kc for two times

the reverse reaction?

a) - 2Kc

b) -Kc

c) (Kc)-2

d) none of these

5) A reaction reaches dynamic equilibrium at a given temperature when

a) the amount of products exceeds the amount of reactants.

b) kfwd equals krev.

c) opposing reactions cease and the system is static.

d) the relative amounts of reactants and products are constant and

the rate of the forward reaction equals the rate of the reverse reaction.

6) What is Kp at 1273 °C for the reaction

2 CO (g) + O2 (g) ∏ 2 CO2 (g)

if Kc is 2.24 x 1022 at the same temperature?

a) 1.35 b) 5.66 x 10-21 c) 1.77 x 1020 d) 5.66 x 1021

7) At a certain temperature bromine and nitric oxide react to form nitrosyl bromide:

Br2 (g) + NO (g) ∏ 2 NOBr (g)

When initial amounts of Br2, NO, and NOBr are mixed, the concentration of

NOBr increases. Which statement below is true about the initial mixture?

a) Kc = Qc

b) Kc < Qc

c) Kc > Qc

d) more information is needed to make a statement about Kc.

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8) The equilibrium constant Kp equals 3.40 at 25°C for the isomerization reaction

cis-2-butene trans-2-butene

If a flask initially contains 1.00 atm of each gas, in what direction will the

reaction proceed to reach equilibrium?

a) It will proceed to the left. b) It will proceed to the right.

c) It is already at equilibrium. d) Not enough information.

9) Which statement about the change of a concentration of a solid during a reaction

is most correct?

a) As a solid is consumed in a reaction its concentration decreases.

b) As a solid is formed in a reaction its concentration increases.

c) Both statements a) and b) are correct.

d) The concentration of a solid does not change during a reaction as long as some

of the solid remains in the reaction mixture.

10) Once the following equation has been correctly balanced, determine which of the

following equilibrium constant expressions for Kc best applies.

C (s) + H2O (g) C2H5OH (g) + O2 (g) (not balanced)

a) [ ] [[ ] [ ]

]OHC

OOHHCK2

252c = b) [ ] [ ]

[ ] [ ]3 2

2 252

c OHCOOHHCK =

c) [ ] [[ ]

]OH

OOHHCK2

252c = d) [ ] [ ]

[ ]3 2

252c OH

OOHHCK =

11) Explain why equilibrium can be generally described as a steady state even though

both the forward and reverse reactions continue to occur.

a) The changes in concentrations occur over very long periods of time and are not

observed.

b) The composition does not appear to change, but the reactions are occurring at

different rates.

c) The composition does not change because the forward and reverse reactions

are very slow.

d) The composition of the system does not change because the reactions occur at

equal rates.

12) In a heterogeneous reaction, why are the concentrations of solids not included in

the equilibrium constant expression?

a) Solids do not take part in chemical reactions.

b) The concentration of the solid does not vary during the reaction.

c) The surface area is more important than the concentration.

d) Reactions involving solids do not go to equilibrium.

13) What is the reaction quotient?

a) It is similar to K but does not include the exponents from the reaction.

b) It is the inverse of K and can reflect any set of reaction conditions.

c) It has the same mathematical form as K but can have any concentration values.

d) It is a value that is always less that K, indicating reaction must occur.

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14) Which of the following changes to an equilibrium mixture of the reaction

5 C (s) + 2 SO2 (g) → CS2 (l) + 4 CO (g) ∆H° = 239.9 kJ

will not result in an increase in the amount of carbon monoxide?

a) Adding carbon. b) Adding sulfur dioxide.

c) Increasing the temperature. d) Increasing the volume of the container.

Chapter 14 Shorter Answer 1) For the following system in equilibrium

SO2(g) + 2 H2S(g) ∏ 2 H2O(g) + 3 S(s) ∆H° = 146 kJ

explain which direction, if either, the equilibrium will shift in response to each of

the following.

a) Reducing the temperature

b) Reducing the concentration of SO2(g)

c) Reducing the concentration of H2O(g)

d) Adding an inert gas such as argon

e) Adding S(s)

f) Reducing the volume of the container

g) Adding a catalyst

2) For the following system in equilibrium

4 KO2(s) + 2 CO2(g) ∏ 2 K2CO3(s) + 3 O2(g) ∆H° = -351 kJ

explain which direction, if either, the equilibrium will shift in response to each of

the following.

a) Increasing the temperature

b) Increasing the concentration of CO2(g)

c) Increasing the concentration of O2(g)

d) Adding an inert gas

e) Removing some K2CO3(s)

g) Increasing the volume of the container

g) Adding a catalyst

3) A mixture of carbon monoxide, hydrogen and methanol is at equilibrium

according to the equation:

CO (g) + 2 H2 (g) ∏ CH3OH (g)

If at 250 °C you have 0.0960 mol⋅L-1 of CO, 0.1910 mol⋅L-1 of H2, and 0.0150

mol⋅L-1 of CH3OH in the equilibrium mixture, then what are the values of Kc and

Kp for this reaction at 250 °C?

4) Suppose we know equilibrium constants for the following two reactions:

GeO (g) + GeW2O7 (g) 2 GeWO4 (g) K = 1.8 x 10-1

GeW2O7 (g) GeO (g) + W2O6 (g) K = 2.6 x 10-5

What is the equilibrium constant for the following reaction?

2 GeO (g) + W2O6 (g) 2 GeWO4 (g)

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5) Briefly describe the effect adding a catalyst will have on a chemical system that is

at equilibrium.

6) Define Le Châtelier’s Principle.

Chapter 14 Problems 1) When solid ammonium carbamate, NH4CO2NH2, is placed in a 1.00 L flask and

allowed to come to equilibrium according to the following equation at 37 °C, 1.01

mol of the solid dissociates. Calculate Kp for the reaction at 37 °C.

NH4CO2NH2(s) ∏ 2 NH3(g) + CO2(g)

2) H2S(g) at 0.9838 atm pressure and 1.85 g of solid iodine are introduced into an

evacuated 725 mL flask at 60 °C. Calculate the total pressure in the flask when the

following equilibrium is established. Kp at 60 °C is 1.34 x 10-5.

H2S(g) + I2(s) ∏ 2 HI(g) + S(s)

3) A mixture of 2.00 mol of nitrogen and 6.00 mol of hydrogen was allowed to come

to equilibrium at 530 K in a closed container of volume 2.00 L. The equilibrium

concentration of ammonia gas was found to be 1.73 mol⋅L-1. Calculate the

equilibrium constant, Kp, at this temperature for the reaction

N2(g) + 3 H2(g) ∏ 2 NH3(g)

4) The reaction PCl3 (g) + Cl2 (g) ∏ PCl5 (g) has the equilibrium constant value

Kp = 0.0870 at 300 °C. A flask starts initially with 0.300 atm of PCl3, 0.500 atm

of Cl2, and 0.200 atm of PCl5. Calculate the equilibrium partial pressures of each

of the gasses.

5) The value of Kc for: 2 H2S(g) ∏ 2 H2(g) + S2(g) is 4.20 x 10-6 at 830 oC.

a) If the initial concentrations of gases are [H2S] = 1.00 M and [H2] = [S2] =

0.500 M, show that the system is not at equilibrium and determine which

direction the reaction must proceed to reach equilibrium.

b) Calculate the expected concentrations of each gas if 0.0700 mol of H2S is

placed in an otherwise empty 1.00L container and allowed to equilibrate.

6) Nitrogen gas reacts with oxygen gas to give nitric oxide

N2 (g) + O2 (g) 2 NO (g) KC = 0.0123 at 3900 °C.

A flask at 3900 °C starts with an initial reaction mixture of

0.105 mol⋅L-1 of N2, 0.105 mol⋅L-1 of O2, and 0.200 mol⋅L-1 of NO.

Calculate the equilibrium concentrations of each of the gases.

- 15 -


7) At 2200 °C, a reaction mixture for the reaction

CH4 (g) + 2 H2S (g) ⇌ CS2 (g) + 4 H2 (g)

is put together where the concentrations of all species are as follows:

[ ] [ ][ ] [ ] 1

21

2

12

14

Lmol 1.56H Lmol 930CSLmol 1.15SH Lmol 1.80CH−−

−−

⋅=⋅=⋅=⋅=

.

If the reaction mixture is allowed to come to equilibrium, we find that we have

lost 87.0 % of the hydrogen gas. Based on this information, what is the value of

Kc for this reaction at 2200 °C?

Chapter 15 Acids and Bases Chapter 15 Multiple Choice 1) Which of the following best describes 0.10 mol L1 HCl(aq)?

a) A dilute solution of a strong base

b) A dilute solution of a weak acid

c) A concentrated solution of a strong acid

d) A dilute solution of a strong acid

e) A concentrated solution of a weak base

2) Which statement is true for the following reaction in aqueous solution?

H2SO4 + HClO4 → H3SO4+ + ClO4

a) H2SO4 is the conjugate base of H3SO4+

b) ClO4 is the conjugate base of H3SO4+

c) H2SO4 and HClO4 are both acting as acids

d) ClO4 is the conjugate acid of HClO4

e) HClO4 is the conjugate acid of H2SO4

3) Which is the weakest acid?

a) HBr b) HCl c) HF d) HI

e) They all have the same strength

4) For the reaction CO(g) + H2(g) ∏ C(s) + H2O(g) the value of Kp equals

a) Kc b) (RT)/Kc c) Kc/(RT) d) Kc(RT) e) None of these

5) Identify the types of acid represented by BF3 in the reaction BF3 + F- → BF4-

a) Arrhenius, Brønsted-Lowry and Lewis

b) Brønsted-Lowry and Lewis

c) Arrhenius only

d) Brønsted-Lowry only

e) Lewis only

- 16 -


6) Which of the following statements is true about ammonia (NH3)?

a) NH4+ is its conjugate acid; NH2

- is its conjugate base.

b) NH4+ is its conjugate acid; it has no conjugate base.

c) It has no conjugate acid; NH2- is its conjugate base.

d) It has neither a conjugate acid or conjugate base.

7) Which one of the following is NOT considered to be a Lewis base?

a) NH4+ b) NH3 c) H2O d) Cl-

8) The compound BF3 can be described as a(n) ______.

a) Arrhenius acid b) Bronsted-Lowry acid

c) Lewis acid d) Lewis base

9) Which of the following statements is NOT one of our definitions of a base?

a) It dissociates in water to give OH-. b) It is an electron pair donor.

c) It is an electron pair acceptor. d) It is a proton acceptor.

10) If the auto-dissociation constant of water, Kw, is 2.4 × 10-14 at human body

temperature (37 °C) then what term best describes a solution that has a pH of

6.81 at 37 °C?

a) acidic b) basic c) neutral d) need more information

11) The ion product constant of water is defined as the

a) product of the concentration of hydrogen ion times the concentration of oxide

ion.

b) product of the hydroxide ion concentration times the hydronium ion

concentration.

c) product of hydronium ion concentration times hydroxide ion concentration

divided by the concentration of water squared.

d) hydronium ion concentration squared times the oxide ion concentration.

12) Which statement is true about an acid-base reaction where we start with equal

amounts of all acids and bases?

a) The stronger acid is found in lesser amounts at equilibrium compared to the

weaker acid.

b) The weaker base is found in greater amounts at equilibrium compared to the

stronger base.

c) Both a) and b) are true

d) Neither a) or b) are true.

13) Which of the following can behave as a Brønsted-Lowry acid or as a Brønsted-

Lowry base in aqueous solution?

a) HSO3- b) NH3 c) HI d) H3PO4

Chapter 15 Shorter Answer 1) Define Brønsted-Lowry base.

2) What is a hydronium ion?

3) What is a strong acid?

- 17 -


4) Use the diagram and the experiment described below to answer the questions

labelled and :

A police crime lab prepares a colourless reference solution of cocaine in water.

Indicator solutions are added to four separate samples of this cocaine solution,

and the following colour data are collected for the samples:

Sample Indicator Solution colour

1 methyl violet violet 2 bromthymol blue blue 3 phenolphtalein colorless 4 alizarin yellow R yellow

Based on this information, what range of pH values (nearest integers only)

must the actual pH of the solution lie in?

Is the solution best described as acidic, basic, or neutral?

5) Give both the Arrhenius and Brønsted-Lowry definitions for acids and bases. If

possible, give an example of a Brønsted-Lowry acid that is not also an Arrhenius

acid. If possible, give an example of a Brønsted-Lowry base that is not also an

Arrhenius base. If an example is not possible, then state that no such example

exists.

Chapter 16 Acid-Base Equilibria Chapter 16 Multiple Choice 1) The pOH (to the correct number of significant figures) of a 3.0 mol·L-1 solution

of hydrochloric acid at 25 °C is:

a) -0.5 b) 0.48 c) 13.5 d) 14.48

2) What is the pH of a 0.020M Ba(OH)2 solution?

a) 1.40 b) 1.70 c) 12.30 d) 12.60

3) What is the hydroxide ion concentration and pH for the hydrochloric acid

solution that has a hydronium ion concentration of 1.50 x 10-4 M?

a) 6.67 x 10-10 M, 4.82 b) 6.67 x 10-10 M, 9.18

c) 6.67 10-11 M, 3.82 d) 6.67 10-11 M, 10.18

- 18 -


4) Methylamine, CH3NH2, has a base dissociation constant of 3.7 x 10-4

What is the conjugate acid of methylamine and what is the value of its acid

dissociation constant?

a) CH3NH3+, 2.7 x 103 b) CH3NH- , 2.7 x 103

c) CH3NH3+, 2.7 x 10-11 d) CH3NH- , 2.7 x 10-11

5) A buffer solution using benzoic acid [HC7H5O2; Ka = 6.3 x 10-5] and sodium

benzoate [NaC7H5O2; Kb of C7H5O2- = 1.6 x 10-10] is prepared in the lab. What

range of values would the pH of the buffer solution probably fall in between?

a) 5.3 – 7.3 b) 0.6 – 2.6 c) 3.2 – 5.2 d) 8.8 - 10.8

6) If an equal number of moles of the weak acid CH3COOH and the strong base

KOH are added to water, which term best describes the resulting solution?

a) acidic b) basic c) neutral d) need more information

7) If the auto-dissociation constant of water, Kw, at 40°C is 2.92 × 10-14 then what is

[H3O+] for a neutral solution in water at 40 °C?

a) 1.00 x 10-7 mol⋅L-1 b) 1.00 x 10-14 mol⋅L-1

c) 2.92 x 10-14 mol⋅L-1 d) 1.71 x 10-7 mol⋅L-1

8) In what way can we increase the buffer capacity of a buffer solution?

a) We can increase the concentration while maintaining the volume.

b) We can increase the volume while maintaining the concentration.

c) Both a) and b) will increase buffer capacity.

d) Neither a) or b) will increase buffer capacity.

9) Which statement about buffers is true?

a) Buffers resist change in pH upon addition of small amounts of strong acid or

strong base.

b) A buffer does not change pH on addition of a strong acid or strong base.

c) Buffers consist of a strong acid and its conjugate base.

d) Buffers have a pH = 7.

10) When the salt ammonium nitrite NH4NO2 is placed in water, the resulting solution

will be:

a) basic. b) neutral. c) acidic. d) need Ka and Kb information.

Chapter 16 Shorter Answer 1) A solution of NaCN will be (acidic, basic, neutral). Choose the correct word in

the brackets and explain your choice.

2) Using the appropriate equations, indicate whether a solution of ammonium

bromide, NH4Br, is acidic, basic or neutral.

3) For a conjugate acid/base pair, the product of Ka and Kb is equal to the ionization

product for water, Kw. Using appropriate equations and the weak acid acetic acid,

CH3COOH, show that this is true.

- 19 -


4) Using the appropriate equations, indicate whether a solution of ammonium

cyanide, NH4CN, is acidic, basic or neutral.

Kb = 2.03 x 10-5 for CN- and Ka = 5.65 x 10-10 for NH4+.

5) Define percent ionization for an acid.

6) Identify the conjugate acid/base pairs for the following equilibrium. Identify the

strongest base present and explain your answer.

HF(aq) + OCl-(aq) ∏ F-(aq) + HOCl(aq) K = 2.2 x 104

7) The following table relates conjugate acid-base pairs, the values of their

dissociation constants in water at 25 °C, and their relative strengths (from

strongest to weakest). Complete the table by filling in all the blanks.

Ka Conjugate acid Conjugate base Kb

6.2 x 10-8 H2PO4-

OH- 55.6

HNO2 2.2 x 10-11

1.1 x 10-8 N2H4

Strongest acid _____ > _____ > _____ > ______ Weakest acid

Strongest base ______ > ______ > ____ > ______ Weakest base

8) Below is given a list of three cations and three anions. Where meaningful, the

acid or base dissociation constants for the ions at 25 °C are also given:

Cations: C5H5NH+ Ka = 5.9 x 10-6 Na+ NH4

+ Ka = 5.6 x 10-10

Anions: Cl- F- Kb = 1.5 x 10-11 CN- Kb = 2.0 x 10-5

There are nine possible salts we can make from combining these ions. Write the

chemical formula for each of the nine salts in the appropriate column of the

table below based on whether the salt will give an acidic, basic, or neutral solution

when it is dissolved in water at 25 °C.

Acidic Basic Neutral

Chapter 16 Problems 1) Determine the resulting pH when the following pairs of solutions are mixed. The

Ka for CH3COOH is 1.8 x 10-5, and Kb for NH3 is 1.8 x 10-5.

a) 50.0 mL of 0.150 mol⋅L-1 CH3COOH and 25.0 mL of 0.300 mol⋅L-1 NaOH

b) 70.0 mL of 0.150 mol⋅L-1 NH3 and 30.0 mL of 0.350 mol⋅L-1 HCl

2) Calculate the percent ionization of 0.025 mol⋅L-1 HNO2, where Ka = 7.2 x 10-4.

- 20 -


3) Aniline (C6H5NH2, Kb = 4.3 x 10-10 at 25 °C) is an industrially important amine

used in the making of dyes. Determine the pH of an aniline solution made by

dissolving 6.90 g of aniline in enough water to make 100 mL of solution.

4) Determine the acid dissociation constant, Ka, for a 0.010M nitrous acid (HNO2)

solution that has a pH of 2.70.

5) What is the pH of a solution made by adding 0.100 mol of acetic acid,

CH3COOH, to water and making up to a total volume of 1L? Ka = 1.8x10-5 for

acetic acid.

6) A 0.100 M solution of chloroacetic acid (ClCH2COOH) is 11.0 % ionized.

Using this information, determine [ClCH2COO-], [H3O+], [ClCH2COOH] and

Ka for chloroacetic acid.

7) A 0.200 mol/L aqueous solution of the weak base ethylamine, C2H5NH2, is found

to have a pH of 11.49 at 25 °C. Calculate Kb for ethylamine.

8) For an experiment requiring a constant pH, a buffer solution is prepared by

dissolving 1.51 g of ammonia [NH3; molar mass = 17.031 g·mol-1] and 2.86 g of

ammonium nitrate [(NH4)2NO3; molar mass = 98.082 g·mol-1] in water to give

0.500 L of solution.

a) If the acid dissociation constant for the ammonium ion is 5.6 x 10-10, what is

the pH of the buffer solution?

b) If 0.88 g of NaOH [molar mass = 39.997 g·mol-1] is added to the buffer

solution with no change in the solution volume, what is the pH?

9) a) Calculate the pH of a buffer solution created by placing 0.020 mol of

acetylsalicylic acid, HC9H7O4 [Ka = 3.0 x 10-4], and 0.025 mol of potassium

acetylsalicylate KC9H7O4 into enough water to make 1.00 L of solution.

b) If we take our buffer solution in part a) and add 0.0070 moles of sodium

hydroxide, what is the pH of the solution if the volume does not change?

10) A 0.208 M solution of iodic acid (HIO3) is found to have a pH of 0.917 at 25 °C.

a) What is the value of the acid dissociation constant Ka of iodic acid at 25 °C?

b) What is the percent ionization of this iodic acid solution?

11) a) Calculate the pH of a buffer solution created by placing 0.080 mol of

hydrocyanic acid, HCN [Ka = 6.2 x 10-10], and 0.065 mol of potassium cyanate,

KCN into enough water to make 1.00 L of solution.

b) If we take our buffer solution in part a) and add 0.035 moles of hydrochloric

acid, what is the pH of the solution if the volume does not change?

- 21 -


Chapter 17 Solubility Equilibria Chapter 17 Multiple Choice

1) What is the solubility product constant for the slightly soluble salt Ca3(PO4)2?

a) b) [ ] [ ] 2 3 4

3 2sp POCaK −+=

[ ] [ ]( )[ ]24

2 3 4

3 2

sp PO CaPOCaK

−+

=

c) ( )[ ]

[ ] [ ] 2 3 4

3 224

spPOCa

PO CaK

−+= d) [ ] [ ] 2 3

43 2sp

POCa1K

−+=

2) Precipitation of an ionic compound will occur upon mixing of desired reagents if

the initial ion product is

a) equal to the Ksp b) less than the Ksp c) greater than the Ksp

d) none of the above

Chapter 17 Shorter Answer 1) What is the molar solubility for copper (II) phosphate [Cu3(PO4)2] if the Ksp of

copper (II) phosphate is 1.4 x 10-37?

Chapter 17 Longer Answer 1) Chromium (III) hydroxide [Cr(OH)3] has a Ksp of 6.7 x 10-31 at 25 °C, while tin

(II) hydroxide [Sn(OH)2] has a Ksp of 5.4 x 10-27 at 25 °C. Calculate the molar

solubilities for both metal hydroxides. Which has the greater molar solubility,

chromium (III) hydroxide or tin (II) hydroxide?

2) If the solubility product constant Ksp is 7.4 x 10-11 for magnesium fluoride

(MgF2), will a precipitate form when 20.0 mL of a 1.0 x 10-6 mol·L-1 solution of

Mg2+ ions is added to 80.0 mL of a 1.0 x 10-6 mol·L-1 solution of F- ions?

3) In a laboratory, we can completely dissolve 0.00100 moles of lead (II) iodide into

exactly one litre of solution. If we take this solution and add 200.0 mL of a

solution of iodide ions with a concentration of 0.0350 mol⋅L-1, will precipitation

occur after the mixing of the solutions?

The Ksp of lead (II) iodide (PbI2) is 8.6 x 10-9.

Chapter 19 Electrochemistry Chapter 19 Multiple Choice

1) In a galvanic cell the half-reaction

MnO4- (aq) + 8 H+ (aq) + 5 e- → Mn2+ (aq) + H2O (l)

a) is an oxidation half-reaction that occurs at the anode.

b) is an oxidation half-reaction that occurs at the cathode.

c) is a reduction half-reaction that occurs at the anode.

d) is a reduction half-reaction that occurs at the cathode.

- 22 -


2) Which of the following terms can be used to describe an electrochemical cell in

which a spontaneous chemical reaction generates an electric current?

I. an electrolytic cell

II. a galvanic cell

III. a voltaic cell

a) I only. b) II only. c) Both I and II. d) Both II and III.

Chapter 19 Shorter Answer 1) A galvanic cell is constructed so the following reaction occurs

Ni (s) + 2 Ag+ (aq) → Ni2+ (aq) + 2 Ag (s)

a) What is the shorthand notation for this galvanic cell?

b) Use the following data

Ag+ (aq) + e- → Ag (s) E°red = +0.80 V

Ni2+ (aq) + 2 e- → Ni (s) E°red = -0.26 V

to calculate the standard cell potential for the reaction.

Chapter 19 Longer Answer 1) A specific galvanic cell can be described in shorthand notation as

V (s) | V2+ (aq) || Cu2+ (aq) | Cu (s) E°cell = 1.47 V

In each half-cell, the nitrate salts of the metals are found in solution, and the salt

bridge contains aqueous sodium nitrate. Draw a picture of the galvanic cell, being

sure to show the information listed in parts a) to d) below. Then answer the

remaining questions about the cell.

a) label the electrodes by metal symbol.

b) show which electrode is positive, and which is negative.

c) show the metal ions in each half-cell and show with an arrow whether they

move toward or away from the electrode.

d) show the direction of electron flow through the wire with an arrow.

e) What is the anode half-cell reaction?

f) What is the cathode half-cell reaction?

g) What is the overall cell reaction?

h) If the standard reduction potential for the Cu/Cu2+ half-cell is 0.34 V, what is

the standard reduction potential for the V/V2+ half-cell?

2) How many grams of solid cadmium are deposited from an aqueous solution of

cadmium sulphate (CdSO4) in an electrolytic cell when an electric current of 1.51

A flows through the solution for 156 minutes? Is the cadmium deposited at the

cathode of the cell, or at the anode?

- 23 -


3) A specific galvanic cell can be described by the following paragraph:

“Solid lead [Pb] is oxidized to aqueous lead (II) ions [Pb2+] in one half-cell,

which is connected by a salt bridge to a second half-cell where liquid bromine

[Br2] is reduced to aqueous bromide ions [Br-] on the surface of a solid

platinum electrode. The two electrodes are connected by a wire.”

Use the information in the paragraph to answer Parts a) to e):

a) What is the shorthand notation used to represent this particular galvanic cell?

b) What is the oxidation half-cell reaction?

c) What is the reduction half-cell reaction?

d) What is the overall cell reaction?

e) If the standard reduction potential for the Br2/Br- half-cell is 1.09 V and the

standard reduction potential for the Pb/Pb2+ half-cell is -0.13 V, then what is the

standard cell potential?

4) What mass of solid aluminum is created from a molten mixture containing

aluminum ions (Al3+) in an electrolytic cell when an electric current of 7.59 A

flows through the solution for 5.11 days?

5) A galvanic cell is constructed so the following reaction occurs

Ni (s) + 2 Ag+ (aq) → Ni2+ (aq) + 2 Ag (s)

a) What is the shorthand notation for this galvanic cell?

b) Which substance is considered the cathode for this cell?

c) Use the following data

Ag+ (aq) + e- → Ag (s) E°red = +0.80 V

Ni2+ (aq) + 2 e- → Ni (s) E°red = -0.26 V

to calculate the standard cell potential for the reaction.

6) Elemental calcium is produced by the electrolysis of molten CaCl2. What mass of

calcium (in kilograms) can be produced in this process if a electric current of

5.55 x 103 amperes is applied to the electrolytic cell for 48.0 hours?

7) An unknown platinum salt is melted. Since the identity of the salt is unknown,

then the charge on the platinum ion is also unknown, and therefore one of the

reactions that occur when electrolysis is performed on the solution can only be

expressed as

Pt n+ (l) + n e- → Pt (s)

If 2.00 h of electrolysis of the molten salt with a current of 2.50 A results in the

formation of 9.09 g of solid platinum, then what must the charge be on the

platinum ion of the unknown salt?

- 24 -


8) A voltaic cell is created where one half-cell contains a bar of chromium immersed

in a Cr(NO3)3 solution, while the other half-cell has a silver bar in a AgNO3

solution. The two half cells are joined by a salt bridge containing KNO3, and a

wire connects the two metal bars. Measurements indicate the Cr bar is negative in

comparison to the Ag bar.

Based on this information, use the template below to provide the following

information.

i) Label each electrode by metal type, indicate whether it is the anode

or cathode, and show the sign of each electrode.

ii) Within each half-cell write the correct balanced half-reaction.

iii) Indicate the direction of electron flow through the wire.

iv) Label the ions of the salt bridge and indicate their direction of

movement.

- 25 -

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