Question

QUESTION 5

Consider the formation of solid silver chloride from aqueous silver and chloride ions.

Given the following table of thermodynamic data at 298 K:

  
  
The value of K for the reaction at 25 °C is ________.

a)		1.8 × 104
b)		3.7 × 1010
c)		1.9 × 10-10
d)		810
e)		5.3 × 109

QUESTION 6

Consider the reaction:  

NH ₃ (g) + HCl (g) → NH ₄Cl (s)

Given the following table of thermodynamic data,

  

determine the temperature (in °C) above which the reaction is nonspontaneous.

a)		This reaction is spontaneous at all temperatures.
b)		432.8
c)		1235
d)		618.1
e)		345.0

QUESTION 7

For the reaction

2 C ₄H ₁₀ (g) + 13 O ₂ (g) → 8 CO ₂ (g) + 10 H ₂O (g)

ΔH° is -125 kJ/mol and ΔS° is +253 J/K ∙ mol. This reaction is ________.

a)		spontaneous only at low temperature
b)		spontaneous only at high temperature
c)		spontaneous at all temperatures
d)		nonspontaneous at all temperatures
e)		unable to determine without more information

QUESTION 8

The second law of thermodynamics states that ________.

a)		for any spontaneous process, the entropy of the universe increases
b)		the entropy of a pure crystalline substance is zero at absolute zero
c)		ΔS = qrev/T at constant temperature
d)		ΔH°rxn = Σ nΔH°f (products) - Σ mΔH°f (reactants)
e)		ΔE = q + w

QUESTION 9

The value of ΔS° for the catalytic hydrogenation of ethene to ethane,

C₂H₄ (g) + H₂(g) → C₂H₆ (g)

is ________ J/K ∙ mol.

a)		-120.5
b)		-232.5
c)		+101.9
d)		-101.9
e)		+112.0

QUESTION 10

Refer to the data in the table given in problem 9.


The value of ΔS° for the catalytic hydrogenation of acetylene to ethene,

C₂H₂ (g) + H₂ (g) → C₂H₄ (g)

is ________ J/K∙ mol.

a)		-112.0
b)		+112.0
c)		+18.6
d)		+550.8
e)		-18.6

QUESTION 11

Refer to the data in the table given in problem 9.


The combustion of acetylene in the presence of excess oxygen yields carbon dioxide and water:

2C₂H₂ (g) + 5O₂ (g) → 4CO₂ (g) + 2H₂O (l)

The value of ΔS° for this reaction is ________ J/K ∙ mol.

a)		+689.3
b)		+432.4
c)		-432.4
d)		-122.3
e)		+122.3

QUESTION 12

Refer to the data in the table given in problem 9.


The value of ΔS° for the reaction

2C (s, diamond) + O₂ (g) → 2CO (g)

is ________ J/K ∙ mol.

a)		+9.5
b)		+185.9
c)		-9.5
d)		-185.9
e)		-195.7

QUESTION 13

What is the ΔG° (kJ/mol) for the reaction shown below of silver chloride dissolving at 25 °C? K_sp = 1.8 × 10^-10M².

∆G^o = ___ kJ/mol (Answer to two significant figures.)

QUESTION 14

Which one of the following statements is true about the equilibrium constant for a reaction if ΔG° for the reaction is negative?

a)		K < 1
b)		K = 0
c)		K > 1
d)		K = 1
e)		More information is needed.

QUESTION 15

For PbBr2, Ksp = 6.60∙10-6 M3. What is the molar solubility (S) of PbBr2?

S = ___ M

QUESTION 16

What is the molar solubility (S) of PbCl2 in 1.00x10-3 M NaCl? (For PbCl₂, K_sp = 1.6 x 10^-6 M³)

S = ___ M

QUESTION 17

Calculate the solubility (S) of CuX (Ksp=[Cu2+][X2−]=1.27∙10−36 M2) in a solution that is 0.100 M in NaCN.

(K_f for Cu(CN)₄^2- is 1.0 x 10²⁵ M^-4.)

S = ___ x 10^-8 M

Answer 1

Question 5.

The Ksp of AgCl(s) = 1.8*10^-10

Ag⁺(aq) + Cl^-(aq) $\rightleftharpoons$ AgCl(s); K = 1/Ksp

Therefore, K = 1/1.8*10^-10 = 5.556*109 ~ 5.3*10⁹ (Option E)