Hannah

Graph

Substance ΔG°f(kJ/mol)

M2O3(s)         −6.70

M(s)                  0

O2(g)                0

Question

Consider the decomposition of a metal oxide to its elements, where M represents a generic metal.

M2O3(s)↽−−⇀ 2M(s)+32O2(g)

What is the standard change in Gibbs energy for the reaction, as written, in the forward direction?

Δ𝐺∘rxn=

kJ/mol

What is the equilibrium constant of this reaction, as written, in the forward direction at 298 K?

𝐾=

What is the equilibrium pressure of O2(g) over M(s) at 298 K?

𝑃O2=

atm

A reaction

A(aq)+B(aq)↽−−⇀C(aq)

has a standard free‑energy change of −3.51 kJ/mol at 25 °C.

What are the concentrations of A, B, and C at equilibrium if, at the beginning of the reaction, their concentrations are 0.30 M, 0.40 M, and 0 M, respectively?

[A]=

M

[B]=

M

[C]=

M

How would your answers change if the reaction had a standard free‑energy change of +3.51 kJ/mol?

All concentrations would be higher.

All concentrations would be lower.

There would be no change to the answers.

There would be less A and B but more C.

There would be more A and B but less C.

Consider the data in the table.

Compound Melting point (°C) 𝚫𝐇𝐟𝐮𝐬 (𝐤𝐉/𝐦𝐨𝐥) Boiling point (°C) 𝚫𝐇𝐯𝐚𝐩 (𝐤𝐉/𝐦𝐨𝐥)

HF −83.11 4.577 19.54 25.18

HCl −114.3 1.991 −84.9 17.53

HBr −86.96 2.406 −67.0 19.27

HI −50.91 2.871 −35.38 21.16

Using the data in the table, calculate Δ𝑆fus and Δ𝑆vap for HBr.

Δ𝑆fus=

J/(K⋅mol)

Δ𝑆vap=

J/(K⋅mol)

Determine the entropy change when 3.00 mol HBr(l) freezes at atmospheric pressure.

Δ𝑆=

J/K

When the oxide of generic metal M is heated at 25.0 ∘C , a negligible amount of M is produced.

MO2(s)↽−−⇀M(s)+O2(g)Δ𝐺∘=290.2kJmol

When this reaction is coupled to the conversion of graphite to carbon dioxide, it becomes spontaneous.

What is the chemical equation of this coupled process? Show that the reaction is in equilibrium. Include physical states and represent graphite as C(s) .

chemical equation:

What is the thermodynamic equilbrium constant for the coupled reaction?

𝐾=

A critical reaction in the production of energy to do work or drive chemical reactions in biological systems is the hydrolysis of adenosine triphosphate, ATP, to adenosine diphosphate, ADP, as described by the reaction

ATP(aq)+H2O(l)⟶ADP(aq)+HPO2−4(aq)

for which Δ𝐺∘rxn=−30.5 kJ/mol at 37.0 °C and pH 7.0. Calculate the value of Δ𝐺rxn in a biological cell in which [ATP]=5.0 mM, [ADP]=0.90 mM, and [HPO2−4]=5.0 mM.

Δ𝐺rxn=

kJ/mol

Is the hydrolysis of ATP spontaneous under these conditions?

-yes

-no

Consider the following reaction at 298 K.

2H2(g)+O2(g)⟶2H2O(g)Δ𝐻∘=−483.6 kJ

Calculate the following quantities. Refer to the standard entropy values as needed.

Δ𝑆sys=

J/K

Δ𝑆surr=

J/K

Δ𝑆univ=

J/K

Consider the table.

Metal Tm (K) ΔHfus (kJ/mol) Tb (K) ΔHvap (kJ/mol)

Li 454 2.99 1615 134.7

Na 371 2.60 1156 89.6

K 336 2.33 1033 77.1

Rb 312 2.34 956 69

Cs 302 2.10 942 66

Using the data, calculate Δ𝑆fus and Δ𝑆vap for Cs.

Δ𝑆vap=

JK⋅mol

Δ𝑆fus=

JK⋅mol

Consider the following reaction at 298 K.

2H2(g)+O2(g)⟶2H2O(g)Δ𝐻∘=−483.6 kJ

Calculate the following quantities. Refer to the standard entropy values as needed.

Δ𝑆sys=

J/K

Δ𝑆surr=

J/K

Δ𝑆univ=

J/K

Graph given

Compound Δ𝐺∘f (kJ/mol)

A +387.7

B +550.2

C +402.0

Use the data given here to calculate the values of Δ𝐺∘rxn at 25 ∘ C for the reaction described by the equation

A+B↽−−⇀C

Δ𝐺∘rxn=

kJ

If Δ𝐻∘rxn and Δ𝑆∘rxn are both positive values, what drives the spontaneous reaction and in what direction at standard conditions?

The spontaneous reaction is

entropy-driven to the left.

enthalpy-driven to the left.

entropy-driven to the right.

What is the value of 𝐾 for this aqueous reaction at 298 K?

A+B↽−−⇀C+DΔ𝐺°=

11.71 kJ/mol

𝐾=?????????????

For a gaseous reaction, standard conditions are 298 K and a partial pressure of 1 atm for all species.

For the reaction

2NO(g)+O2(g)↽−−⇀2NO2(g)

the standard change in Gibbs free energy is Δ𝐺°=−72.6 kJ/mol . What is ΔG for this reaction at 298 K when the partial pressures are 𝑃NO=0.150 atm , 𝑃O2=0.350 atm , and 𝑃NO2=0.900 atm ?

Δ𝐺=

TOOLS

x10y

kJ/mol

With two dice, each numbered 1–6, there are two possible ways to roll a 3.

One possibility shows the first die at 1 and the second die at 2. The other possibility shows the first die at 2 and the second die at 1.

Thus, for the outcome of 3 (a particular macrostate), there are 2 microstates.

How many possible ways are there to roll a 5 ?

number of ways to roll a 5 :

What is the entropy associated with an outcome of 5 ?

𝑆=

J/K

Consider an amphoteric hydroxide, M(OH)2(s) , where M is a generic metal.

M(OH)2(s)↽−−⇀M2+(aq)+2OH−(aq)𝐾sp=7×10−16

M(OH)2(s)+2OH−(aq)↽−−⇀[M(OH)4]2−(aq)𝐾f=0.03

Estimate the solubility of M(OH)2 in a solution buffered at pH = 7.0, 10.0, and 14.0.

solubility at pH = 7.0

M

solubility at pH = 10.0

M

solubility at pH = 14.0

M

You need to prepare 100.0 mL of a pH 4.00 buffer solution using 0.100 M benzoic acid (p𝐾a=4.20) and 0.220 M sodium benzoate.

How many milliliters of each solution should be mixed to prepare this buffer?

benzoic acid:

mL

sodium benzoate:

ml

osphoric acid is a triprotic acid ( 𝐾a1=6.9×10−3 , 𝐾a2=6.2×10−8 , and 𝐾a3=4.8×10−13 ).

To find the pH of a buffer composed of H2PO−4(aq) and HPO2−4(aq) , which p 𝐾a value should be used in the Henderson–Hasselbalch equation?

A 𝐾a1 = 2.16

B 𝐾a2 = 7.21

C 𝐾a3 = 12.32

Calculate the pH of a buffer solution obtained by dissolving 14.0 g of KH2PO4(s) and 25.0 g of Na2HPO4(s) in water and then diluting to 1.00 L.???

A generic salt, AB2 , has a molar mass of 257 g/mol and a solubility of 3.30 g/L at 25 °C.

AB2(s)↽−−⇀A2+(aq)+2B−(aq)

What is the 𝐾sp of this salt at 25 °C?

𝐾sp=

At 22 °C, an excess amount of a generic metal hydroxide, M(OH)2, is mixed with pure water. The resulting equilibrium solution has a pH of 10.14. What is the 𝐾sp of the salt at 22 °C?

𝐾sp=

Above what Fe2+ concentration will Fe(OH)2 precipitate from a buffer solution that has a pH of 9.26 ?

The 𝐾sp of Fe(OH)2 is 4.87×10−17.

[Fe2+]=

M

Write the balanced chemical equation for each of the reactions. Include phases.

When aqueous sodium hydroxide is added to a solution containing lead(II) nitrate, a solid precipitate forms.

equation:

However, when additional aqueous hydroxide is added, the precipitate redissolves, forming a soluble [Pb(OH)4]2−(aq) complex ion.

equation:

Consider an amphoteric hydroxide, M(OH)2(s) , where M is a generic metal.

M(OH)2(s)↽−−⇀M2+(aq)+2OH−(aq)𝐾sp=7×10−16

M(OH)2(s)+2OH−(aq)↽−−⇀[M(OH)4]2−(aq)𝐾f=0.03

Estimate the solubility of M(OH)2 in a solution buffered at pH = 7.0, 10.0, and 14.0.

solubility at pH = 7.0

M

solubility at pH = 10.0

M

solubility at pH = 14.0

M