Deck 11: Chemical Equilibria

Question 1

Consider the reaction CuSO₄(s) $\rightarrow$ CuO(s)+ SO₃(g)
If $\Delta$ G $\degree$ = -14.6 kJ at 950 $\degree$ C for this reaction,what is $\Delta$ G for an SO₃(g)pressure of 20 bar at this temperature.

A)15.9 kJ
B)45.1 kJ
C)(-14.6 kJ)
D)30.5 kJ
E)(-45.1 kJ)

Answer 1

15.9 kJ

Question 2

Calculate $\Delta$ G at 298 K for the reaction C₂H₅OH(l) $\rightarrow$ C₂H₅OH(g,0.0400 bar)
Given $\Delta$ G $\degree$ = 6.2 kJ at 298 K.

A)14 kJ
B)2.7 kJ
C)(-14 kJ)
D)(-1.8 kJ)
E)1.8 kJ

Answer 2

(-1.8 kJ)

Question 3

For the equilibrium N₂O₄(g) 2NO₂(g),plot,on the same graph,the forward and reverse reaction rates as a function of time.If possible,mark on the graph where equilibrium is reached.

Answer 3

Eventually the rate of the forward reaction equals the rate of the reverse reaction-this is equilibrium.

Question 4

Consider the reaction 2CuBr₂(s) $\rightarrow$ 2CuBr(s)+ Br₂(g)
If the equilibrium vapor pressure of Br₂(g)is 1.43 * 10^-5 Torr at 298 K,what is $\Delta$ G at this temperature when Br₂(g)is produced at a pressure of 7.50 * 10^-8 Torr.

A)(-5.65 kJ)
B)13.0 kJ
C)5.65 kJ
D)(-3.42 kJ)
E)(-13.0 kJ)

Question 5

What is the relation between K and K_c for the reaction H₂(g)+ I₂(g) 2HI(g)

A)K = K_c
B)K = RTK_c
C)K_c = (RT)²K
D)K = (RT)²K_c
E)K_c = RTK

Question 6

For the equilibrium CaCO₃(s) CaO(s)+ CO₂(g),(a)represents the composition at equilibrium at a certain temperature.In (b),a small amount of Ca^*CO₃(s)has been added (Ca^*CO₃(s)represents Ca¹⁴CO₃(s)or labeled calcium carbonate).Draw the composition in (c)at equilibrium and explain your drawing.

Question 7

If $\Delta$ G_r^o = 27.1 kJ∙mol^-1 at 25 $\degree$ C for the dissociation of acetic acid in aqueous solution,what is K for the reaction
CH₃COO^-(aq)+ H₃O⁺(aq) CH₃COOH(aq)+ H₂O(l)

Question 8

If a 1-L flask containing D₂(g),N₂(g),and ND₃(g)at equilibrium at 300 K and a 1-L flask of H₂(g),N₂(g),and NH₃(g)at equilibrium at 300 K are mixed,analysis of the reaction mixture shows that HD(g),NHD₂(g),and NH₂D(g)are also present.What conclusion(s)can be drawn?

Question 9

Consider the reaction CuSO₄(s) $\rightarrow$ CuO(s)+ SO₃(g)
If $\Delta$ G $\degree$ = -14.6 kJ at 950 $\degree$ C for this reaction,what is $\Delta$ G for an SO₃(g)pressure of 50 bar at this temperature?

A)2.68 kJ
B)25.2 kJ
C)54.4 kJ
D)16.3 kJ
E)(-54.4 kJ)

Question 10

Consider the following reaction at a certain temperature:
Ni(s)+ 4CO(g) Ni(CO)₄(g)
Calculate K for this reaction if,at equilibrium,the partial pressures of CO(g)and Ni(CO)₄(g)are 1.25 and 6.65 atm over 1.00 kg of nickel.

Question 11

Consider the reaction NO(g)+ O₂(g) $\rightarrow$ NO₂(g)
If $\Delta$ H $\degree$ = -56.52 kJ and $\Delta$ S $\degree$ = -72.60 J.K ^{- 1} at 298 K,what is the equilibrium constant for the reaction at 298 K?

A)1.31 * 10⁶
B)7.63 *10^-7
C)660
D)1.22 * 10¹⁴
E)8.08*10⁹

Question 12

If $\Delta$ G $\degree$ = 27.1 kJ at 25 $\degree$ C for the reaction CH₃COOH(aq)+ H₂O(l) CH₃COO^-(aq)+ H₃O⁺(aq)
What is K_a for this reaction at 298 K?

A)1.15 *10^-11
B)5.63 * 10⁴
C)1.78 *10^-5
D)1.01
E)9.89 *10^-1

Question 13

The equilibrium constant for the reaction
HNO₂(aq)+ H₂O(l) NO₂+(aq)+ H₃O⁺(aq)
is 4.3*10 sup>- ⁴ at 25 $\degree$ C.Will nitrous acid spontaneously dissociate when
[HNO₂(aq)] = [NO₂+(aq)] = [H₃O⁺(aq)] = 1.0 M? Show your calculations.

Question 14

Calculate the value of K at 700 K for the reaction H₂(g)+ I₂(g) 2HI(g)
Given that K_c = 54 at the same temperature.

A)3100
B)2.2
C)54
D)9.3
E)1300

Question 15

The equilibrium constant expression for the reaction
CuSO₄(s) CuO(s)+ SO₃(g)
is K = [CuO(s)][SO₃(g)]/[CuSO₄(s)].True or false?

Question 16

Calculate $\Delta$ G at 298 K for the reaction C₂H₅OH(l) $\rightarrow$ C₂H₅OH(g,0.0263 bar)
Given $\Delta$ G $\degree$ = 6.2 kJ at 298 K.

A)6.2 kJ
B)15 kJ
C)2.8 kJ
D)(-2.8 kJ)
E)(-15 kJ)

Question 17

The equilibrium constant for the reaction
HNO₂(aq)+ H₂O(l) NO₂-(aq)+ H₃O⁺(aq)
is 4.3 *10 ^{- 4} at 25 $\degree$ C.Will nitrous acid spontaneously dissociate when
[HNO₂(aq)] = 1.0 M and [NO₂-(aq)] = [H₃O⁺(aq)] = 1.0 *10 ^{- 5} M?
Show your calculations.

Question 18

Consider the reaction 2Fe₂O₃(s)+ 3C(s) $\rightarrow$ 4Fe(s)+ 3CO₂(g), $\Delta$ H $\degree$ = 462 kJ, $\Delta$ S $\degree$ = 558 J.K ^{- 1}
Calculate the equilibrium constant for this reaction at 525 $\degree$ C.

A)3.04 *10 ^{- 3}
B)8.07 *10 ^{- 2}
C)5.20* 10 ^{- 7}
D)1.9*10⁶
E)2.18 *10 ^{- 2}

Question 19

Consider the reaction 2CuBr₂(s) $\rightarrow$ 2CuBr(s)+ Br₂(g)
If the equilibrium vapor pressure of Br₂(g)is 1.43 *10 ^{- 5} Torr at 298 K,what is $\Delta$ G at this temperature when Br₂(g)is produced at a pressure of 7.50 * 10^-7 Torr?

A)(-7.31 kJ)
B)7.31 kJ
C)39.9 kJ
D)(-3.17 kJ)
E)(-4.15 kJ)

Question 20

Calculate the equilibrium constant for the following reaction at 25 $\degree$ C 2TiCl₃(s)+ 2HCl(g) 2TiCl₄(g)+ H₂(g)
Given $\Delta$ G $\degree$ = +46.6 kJ.

A)3.8 *10^-98
B)1.5 *10^-19
C)6.7 *10^-9
D)6.6 * 10¹⁸
E)1.5 * 10⁸

Question 21

Given: P₄(s)+ 6Cl₂(g)b 4PCl₃(l)
K
Calculate the equilibrium constant for the following reaction.
2PCl₃(l) 3Cl₂(g)+ P₄(s)

A)(-K^1/2 )
B)1/K^1/2
C)1/K²
D)1/K
E)K^1/2

Question 22

The value of K for a given reaction is a constant and does not have units.True or false?

Question 23

Given: C(s)+ CO₂(g) 2CO(g) At equilibrium at a certain temperature,the partial pressures of CO(g)and CO₂(g)are 1.22 atm and 0.780 atm,respectively.Calculate the value of K for this reaction.

A)3.13
B)2.00
C)1.91
D)1.56
E)0.640

Question 24

Given: 2SO₂(g)+ O₂(g) 2SO₃(g) At equilibrium at a certain temperature,the concentrations of SO₃(g),SO₂(g),and O₂(g)are 0.12 M,0.86 M,and 0.33 M,respectively.Calculate the value of K_c for this reaction.

A)1.31
B)0.42
C)0.014
D)0.059
E)0.87

Question 25

The equilibrium constant,K,for the reaction 2HgO(s) 2Hg(l)+ O₂(g)
Is 1.2 *10^-30.Calculate K for the reaction
1/2O₂(g)+ Hg(l) HgO(s).

A)(-1.1 * 10^-15 )
B)8.3 *10²⁹
C)4.2 *10²⁹
D)9.1 *10¹⁴
E)1.1 *10^-15

Question 26

What is the relationship between K and K_c for the reaction below? N₂(g)+ 3H₂(g) 2NH₃(g)

A)K = (RT)⁶K_c
B)K_c = (RT)^-2K
C)K_c = (RT)²K
D)K = (RT)^-2K_c
E)K = (RT)²K_c

Question 27

At 700 K,K = 54 for the reaction H₂(g)+ I₂(g) 2HI(g)
Calculate K_c at 700 K for this reaction.

A)3.2 *10^-4
B)0.94
C)7.7 *10^-4
D)0.45
E)54

Question 28

Given: SO₂(g) O₂(g)+ S(s)
K_c = 2.5 *10^-53
SO₃(g) O₂(g)+ SO₂(g)
K_c = 4.0 *10^-13
Calculate K_c for the reaction
2S(s)+ 3O₂(g) 2SO₃(g)

A)1.6 *10¹⁰³
B)1.6 *10⁸⁰
C)1.0 * 10¹³⁰
D)1.6 * 10⁴⁰
E)1.0 *10⁶⁵

Question 29

Given: 4NH₃(g)+ 5O₂(g) 4NO(g)+ 6H₂O(g)
K
Calculate the equilibrium constant for the following reaction.
2NO(g)+ 3H₂O(g) 2NH₃(g)+ O₂(g)

A)(-0.5K)
B)(-2K)
C)K^-1/2
D)(-K)
E)K^-1

Question 30

Given: 2SO₂(g)+ O₂(g) 2SO₃(g) At equilibrium at a certain temperature,the concentrations of SO₃(g),SO₂(g),and O₂(g)are 0.24 M,0.82 M,and 0.33 M,respectively.Calculate the value of K_c for this reaction.

A)0.89
B)0.21
C)0.79
D)0.26
E)1.04

Question 31

At 25 $\degree$ C,K_c = 1.58 *10^-8 for the reaction NH₄(NH₂CO₂)(s)b 2NH₃(g)+ CO₂(g)
Calculate K at 25 $\degree$ C for this reaction.

A)3.87 *10^-7
B)2.31 *10^-4
C)9.45 *10^-5
D)5.69 *10^-3
E)1.36 *10^-7

Question 32

Given: 4NH₃(g)+ 5O₂(g) 4NO(g)+ 6H₂O(g)
K
Calculate the equilibrium constant for the following reaction.
2NH₃(g)+ O₂(g) 2NO(g)+ 3H₂O(g)

A)K
B)K^-1
C)2K
D)0.5K
E)K^1/2

Question 33

At 25 $\degree$ C,K = 6.9 *10⁵ for the reaction N₂(g)+ 3H₂(g) 2NH₃(g)
Calculate K_c at 25 $\degree$ C for this reaction.

A)2.8* 10⁴
B)6.8 * 10⁵
C)1.1 *10³
D)1.7 * 10⁷
E)4.1 * 10⁸

Question 34

At 600 $\degree$ C,the equilibrium constant for the reaction 2HgO(s) 2Hg(l)+ O₂(g)
Is 2.8.Calculate the equilibrium constant for the reaction 1/2O₂(g)+ Hg(l) HgO(s)

A)(-1.7)
B)1.1
C)0.60
D)0.36
E)1.7

Question 35

The reaction free energy $\Delta$ G_r = $\Delta$ G°_r - RTln(K).True or false?

Question 36

Given: C(s)+ CO₂(g) 2CO(g) At equilibrium at a certain temperature,the partial pressures of CO(g)and CO₂(g)are 1.44 atm and 0.820 atm,respectively.Calculate the value of K for this reaction.

A)2.53
B)10.1
C)1.76
D)3.08
E)3.51

Question 37

At 25 $\degree$ C,K_c = 4.1 *10⁸ for the reaction N₂(g)+ 3H₂(g) 2NH₃(g)
Calculate K at 25 $\degree$ C for this reaction.

A)9.7*10⁷
B)6.9 * 10⁵
C)4.1* 10⁸
D)1.7 *10⁹
E)2.5 *10¹¹

Question 38

What is the relationship between K and K_c for the reaction below? NH₄(NH₂CO₂)(s) 2NH₃(g)+ CO₂(g)

A)K_c = (RT)²K
B)K = RTK_c
C)K = (RT)²K_c
D)K = (RT)³K_c
E)K_c = (RT)³K

Question 39

At 600 $\degree$ C,K_c = 2.8 for the reaction 2HgO(s) 2Hg(l)+ O₂(g)
Calculate K at 600 $\degree$ C for this reaction.

A)6800
B)200
C)1.4 *10⁴
D)2.8
E)138

Question 40

What is the relationship between K and K_c for the reaction below? 2HgO(s) 2Hg(l)+ O₂(g)

A)K_c = (RT)²K
B)K = K_c
C)K_c = RTK
D)K = RTK_c
E)K = (RT)²K_c

Question 41

Which of the following statements is true?

A)When the value of Q is large, the equilibrium lies on the product side of the equilibrium reaction.
B)When the value of K is large, the equilibrium lies on the reactant side of the equilibrium reaction.
C)A small value of K means that the equilibrium concentrations of the reactants are small compared to the equilibrium concentrations of the products.
D)A large value of K means that the equilibrium concentrations of products are large compared to the equilibrium concentrations of the reactants.
E)When the value of K is small, the equilibrium lies on the product side of the equilibrium reaction.

Question 42

For the reaction NH₃(g)+ H₂S(g) NH₄HS(s)
K_c = 9.7 at 900 K.If the initial concentrations of NH₃(g)and H₂S(g)are 2.0 M,what is the equilibrium concentration of NH₃(g)?

A)1.9 M
B)1.7 M
C)0.20 M
D)0.10 M
E)0.32 M

Question 43

A mixture consisting of 0.250 M N₂(g)and 0.500 M H₂(g)reaches equilibrium according to the equation below: N₂(g)3H₂(g) 2NH₃(g)
At equilibrium,the concentration of ammonia is 0.150 M.Calculate the concentration of H₂(g)at equilibrium.

A)0.0750 M
B)0.350 M
C)0.425 M
D)0.275 M
E)0.150 M

Question 44

A mixture consisting of 0.250 M N₂(g)and 0.500 M H₂(g)reaches equilibrium according to the equation below: N₂(g)3H₂(g) 2NH₃(g)
At equilibrium,the concentration of ammonia is 0.150 M.Calculate the concentration of N₂(g)at equilibrium.

A)0.150 M
B)0.100 M
C)0.0750 M
D)0.0500 M
E)0.175 M

Question 45

Consider the reaction PCl₅(g) PCl₃(g)+ Cl₂(g)
At a certain temperature,if the initial concentration of PCl₅(g)is 3.0 M,at equilibrium the concentration of Cl₂(g)is 0.80 M.Calculate the value of K_c at this temperature.

A)0.21
B)0.29
C)0.64
D)3.4
E)0.46

Question 46

Consider the following reaction at a certain temperature: PCl₅(g) PCl₃(g)+ Cl₂(g)
K_c = 0.100
At equilibrium,[PCl₅] = 2.00 M and [PCl₃] = [Cl₂] = 1.00 M.If suddenly 1.00 M PCl₅(g),PCl₃(g),and Cl₂(g)is added,what is the equilibrium concentration of PCl₅(g)?

A)0.65 M
B)4.35 M
C)1.35 M
D)essentially zero
E)2.35 M

Question 47

Consider the reaction
N₂(g)3H₂(g) 2NH₃(g)
If the initial concentrations of nitrogen and hydrogen are each 1.0 M,and X is the equilibrium concentration of ammonia,what is the correct equilibrium expression?

Question 48

Consider the following reaction: Ni(CO)₄(g) Ni(s)+ 4CO(g)
If the initial concentration of Ni(CO)₄(g)is 1.0 M,and x is the equilibrium concentration of CO(g),what is the correct equilibrium relation?

A)K_c = X⁴/(1.0 - 4X)
B)K_c = X/(1.0 - X/4)
C)K_c = X⁴/(1.0 -X/4)
D)K_c = X⁵/(1.0-X/4)
E)K_c = 4X/(1.0 - 4X)

Question 49

For the reaction 2CaSO₄(s) 2CaO(s)+ 2SO₂(g)+ O₂(g)
K = 0.032 at 700 K.What is the total pressure starting from pure CaSO₄(s)?

A)0.22 bar
B)0.011 bar
C)0.60 bar
D)0.20 bar
E)0.40 bar

Question 50

Consider the reaction
Na⁺(g)+ Cl ^- (g) NaCl(s)
If the temperature is lowered,the products/reactants are favored.

Question 51

For the reaction NH₃(g)+ H₂S(g) NH₄HS(s)
K_c = 9.7 at 900 K.If the initial concentrations of NH₃(g)and H₂S(g)are 2.0 M,what is the equilibrium concentration of H₂S(g)?

A)1.9 M
B)0.20 M
C)1.7 M
D)0.10 M
E)0.32 M

Question 52

Consider the following reaction at a certain temperature: PCl₅(g) PCl₃(g)+ Cl₂(g)
K_c = 0.100
At equilibrium,[PCl₅] = 2.00 M and [PCl₃] = [Cl₂] = 1.00 M.If suddenly 1.00 M PCl₅(g),PCl₃(g),and Cl₂(g)is added,what is the equilibrium concentration of Cl₂(g)?

A)3.0 M
B)essentially zero
C)0.65 M
D)2.75 M
E)3.35 M

Question 53

The equilibrium constant,K_c,for the reaction 2NOCl(g) 2NO(g)+ Cl₂(g)
Is 0.51 at a certain temperature.A mixture of NOCl,NO,and Cl₂ with concentrations 1.3,1.2,and 0.60 M,respectively,was introduced into a container at this temperature.Which of the following is true?

A)Cl₂(g)is produced until equilibrium is reached.
B)[NOCl] = [NO] = [Cl₂] at equilibrium.
C)NOCl(g)is produced until equilibrium is reached.
D)[Cl₂] = 0.30 M at equilibrium.
E)No apparent reaction takes place.

Question 54

Consider the following reaction at a certain temperature: PCl₅(g) PCl₃(g)+ Cl₂(g)
K_c = 0.100
At equilibrium,[PCl₅] = 2.00 M and [PCl₃] = [Cl₂] = 1.00 M.If suddenly 1.00 M PCl₃(g)and Cl₂(g)is added,what is the equilibrium concentration of PCl₅(g)?

A)essentially 4.00 M
B)0.58 M
C)2.58 M
D)3.42 M
E)1.42 M

Question 55

At equilibrium,Q = K and $\Delta$ G°_r = 0.

Question 56

Consider the reaction PCl₅(g) PCl₃(g)+ Cl₂(g)
At a certain temperature,if the initial concentration of PCl₅(g)is 2.0 M,at equilibrium the concentration of Cl₂(g)is 0.30 M.Calculate the value of K_c at this temperature.

A)0.064
B)0.053
C)0.090
D)19
E)0.045

Question 57

The equilibrium constant,K_c,for the reaction 2SO₂(g)+ O₂(g) 2SO₃(g)
Is 11.7 at 1100 K.A mixture of SO₂,O₂,and SO₃,each with a concentration of 0.015 M,was introduced into a container at 1100 K.Which of the following is true?

A)SO₂(g)and O₂(g)will be formed until equilibrium is reached.
B)[SO₃] = 0.045 M at equilibrium.
C)[SO₃] = 0.015 M at equilibrium.
D)SO₃(g)will be formed until equilibrium is reached.
E)[SO₃] = [SO₂] = [O₂] at equilibrium.

Question 58

The effect of a volume decrease on the reaction C(s)+ H₂O(g) CO(g)+ H₂(g)
Is

A)that K decreases.
B)more CO(g)and H₂(g)are produced.
C)no change.
D)more H₂O(g)is produced.
E)that K increases.

Question 59

Write the equilibrium constant for 2NaBr(aq)+ Pb(ClO₄)₂(aq) PbBr₂(s)+ 2NaClO₄(aq).

A)K = [Pb²⁺][Br ^- ]²
B)K = 1/([Pb²⁺][Br^-]²)
C)K = [NaClO₄]²/([NaBr]²[Pb(ClO₄)₂]
D)K = [PbBr₂]/([Pb²⁺][Br^-]²)
E)K = 1/([Pb(ClO₄)₂][NaBr]²)

Question 60

Consider the reaction 3Fe(s)+ 4H₂O(g) 4H₂(g)+ Fe₃O₄(s)
If the volume of the container is reduced,

A)the equilibrium constant increases.
B)more H₂(g)is produced.
C)no change occurs.
D)more H₂O(g)is produced.
E)more Fe(s)is produced.

Question 61

Consider the reaction 4NH₃(g)+ 3O₂(g) 2N₂(g)+ 6H₂O(g),K = 10⁸⁰ at a certain temperature.
Initially,all reactants and products have concentrations equal to 12 M.At equilibrium,the approximate concentration of oxygen is

A)6 M.
B)0 M.
C)3 M.
D)12 M.
E)18 M.

Question 62

For the reaction 2NOCl(g) 2NO(g)+ Cl₂(g),K = 98 at a certain temperature.If the equilibrium concentrations in a 1 L container are [NOCl(g)] = 1.0 M,[NO(g)] = 3.5 M and [Cl₂(g)] = 8.0 M,and 2.0 mol of each gas is added,in which direction does the reaction shift?

Question 63

The vapor pressure of acetic acid at 25 $\degree$ C is 16 Torr $\Delta$ G_r for the reaction CH₃COOH(l) CH₃COOH(g)
At 25 $\degree$ C is

A)0
B)+9.57 kJ·mol^-1
C)(-9.57 kJ·mol^-1)
D)+1.85 kJ·mol^-1

Question 64

For any reaction at equilibrium, $\Delta$ G < 0.True or false?

Question 65

Consider the reaction Ni(s)+ 4CO(g) Ni(CO)₄(g)
At 30 $\degree$ C and P_CO = 1 atm,Ni reacts with CO(g)to form Ni(CO)₄(g).At 200 $\degree$ C,Ni(CO)₄(g)decomposes to Ni(s)and CO(g).This means

A)adding an inert gas like argon favors the forward reaction.
B)the activation energy for the forward reaction is greater than for the reverse reaction.
C)the forward reaction is endothermic.
D)K at 30 $\degree$ C is greater than K at 200 $\degree$ C.
E)a decrease in pressure favors the forward reaction.

Question 66

Consider the reaction below:
F₂(g) 2F(g)
(a)Compressing the reaction mixture results in a change in Q.True or false?
(b)Heating the reaction mixture causes the reaction to shift to the left.True or false?
(c)At 1000 K,the equilibrium constant for the reaction is about 10 ^{- 4}.If the reaction is perturbed such that Q = 1,the reaction must shift to the left.True or false?

Question 67

If the equilibrium constant for the reaction Ni(s)+ 4CO(g) Ni(CO)₄(g)is 2.72 at a certain temperature,what is the equilibrium constant for the following reaction at the same temperature?
Ni(CO)₄(g) Ni(s)+ 4CO(g)

Question 68

Consider the reaction
4NH₃(g)+ 7O₂(g) 2N₂O₄(g)+ 6H₂O(g)
If,initially,[NH₃(g)] = [O₂(g)] = 3.60 M,at equilibrium,[N₂O₄(g)] = 0.60 M.Calculate the equilibrium concentrations of all other species.

Question 69

Consider the following
N₂O₄(g) 2NO₂(g)
The equilibrium constant for this reaction will decrease with an increase in temperature.True or false?

Question 70

For the reaction N₂O₄(g) 2NO₂(g)
Which of the following disturbances will cause an increase in NO₂(g)concentration?

A)a decrease in temperature
B)need to know $\Delta$ H for the reaction to predict
C)removal of some N₂O₄(g)
D)an increase in pressure
E)an increase in temperature

Question 71

Consider the reaction 2HI(g) H₂(g)+ I₂(g)
At 298 K,K_c = 1.3 *10^-3,whereas at 783 K,K_c = 2.2 *10^-2.Which of the following is true?

A)The reaction is exothermic.
B)The reaction is endothermic.
C)At 298 K, K = 3.2 *10^-2.
D)At 298 K, the reaction is likely to be spontaneous.
E)At 783 K, more HI(g)is produced.

Question 72

From a plot of Gibbs free energy versus progress of reaction,the sign of $\Delta$ G_r at any point along the curve is given by the slope of the curve.True or false?

Question 73

For the decomposition of ammonia to nitrogen and hydrogen,the equilibrium constant is 1.47*10^-6 at 298 K.Calculate the temperature at which K = 1.00.For this reaction, $\Delta$ H $\degree$ = 92.38 kJ.mol ^{- 1}.

A)193 K
B)353 K
C)466 K
D)492 K
E)219 K

Question 74

For a pure solid or liquid,the molar free energy always has its standard value.True or false?

Question 75

For the reaction 2NOCl(g) 2NO(g)+ Cl₂(g),if,initially,[NOCl(g)] = 2.8 M,at equilibrium [NO(g)] = 1.2 M.Calculate the equilibrium concentration of NOCl(g).

Question 76

Consider the reaction CO(g)+ 2H₂(g) CH₃OH(g)
At room temperature,K is approximately 2*10⁴,but at a higher temperature K is substantially smaller.Which of the following is true?

A)The reaction is endothermic.
B)The value of K_c for this reaction is smaller at all temperatures.
C)At the higher temperature, more CH₃OH(g)is produced.
D)The reaction is exothermic.
E)The reaction becomes spontaneous at higher temperatures.

Question 77

Consider the reaction 4NH₃(g)+ 3O₂(g) 2N₂(g)+ 6H₂O(g),K = 10⁸⁰ at a certain temperature.
Initially,all reactants and products have concentrations equal to 12 M.At equilibrium,the approximate concentration of ammonia is

A)6 M.
B)3 M.
C)12 M.
D)18 M.
E)0 M.

Question 78

If a reaction mixture that is not at equilibrium contains more products than reactants, $\Delta$ G > 0 for the forward reaction.True or false?

Question 79

The equilibrium constant K for the dissociation of N₂O₄(g)to NO₂(g)is 1700 at 500 K.Predict its value at 300 K.For this reaction, $\Delta$ H $\degree$ is 56.8 kJ.mol ^{- 1}.

A)1.32*10^-6
B)1.11*10^-4
C)15.5
D)0.188
E)1.54* 10⁷

Question 80

For the decomposition of ammonia to nitrogen and hydrogen,the equilibrium constant is 1.47 *10 ^{- 6} at 298 K.Calculate the temperature at which K = 0.0100.For this reaction, $\Delta$ H $\degree$ = 92.38 kJ.mol ^{- 1}.

A)241 K
B)332 K
C)59 K
D)390 K
E)117 K