Concepts
Cause & Effect
Equilibrium Concentrations
Kc & Kp
Reaction Quotients
Partial Pressures
Free Energy
Le Châtelier's Principle
100

_____ reactions ultimately reach equilibrium.

reversible 

16.03

100

Answer the question based on the decomposition reaction of carbon dioxide:

3H2(g)+N2(g) ->^2 2NH3(g)

 triangleH=-92.0kJ 

a. Add N2 and the amount of NH3 will...

increase

review sheet

100

Ammonia decomposes and forms an equilibrium mixture with hydrogen and nitrogen according to the given reaction. 

When pure ammonia was placed in a vessel and allowed to reach equilibrium at a given temperature, the mixture was found to contain 0.22 M N2. Calculate the equilibrium concentration of NH3.

The equilibrium constant at that temperature is 250.

2NH3(g) ->^2 N2(g)+3H2(g)

[NH3]=0.016 M

16.35

100

Kp=__(RT) trianglen 

Kc

16.14

100

a. when Qc ? Kc, the reaction proceeds to the right.

b. Qc ? Kc, the reaction proceeds to the left.

c. Qc ? Kc, the reaction is at equilibrium.

a. <

b. >

c. =

16.29

100

What is a helpful tool to use when navigating a partial pressure problem?

an ice table

16.63

100

 triangleG^o: _____ free energy

 triangleG: free energy at _____ point

standard

any

16.69

100

When a _____ is applied to a system at equilibrium, the system, will respond by shifting in the direction that _____ the effect of the _____.

stress

minimizes

stress

16.83

200

For heterogenous reversible reactions, what species are not shown in Kc and why?

solids and pure liquids are constants and do not appear in the Kc expression.

16.11

200

Answer the question based on the decomposition reaction of carbon dioxide:

3H2(g)+N2(g) ->^2 2NH3(g)

 triangleH=-92.0kJ 

a. remove N2 and the amount of H2 will...

increase

review sheet, question 10

200

For the following reaction, Kc at 400 K is 7.0. If 0.50 mol of Br2 and 0.50 mol Cl2 are introduced into a 1.0 L container at 400 K, what will be the equilibrium concentration of BrCl?

Br2(g)+Cl2(g) ->^2 2BrCl(g)

0.285

review sheet, question 7

200

Write the equilibrium expression for each:

a. O2(g)+2H2(g) ->^2 2H2O(l)

b. H2O(g)+C(s) ->^2 CO(g)+H2(g)

a. Kc=[1]/[O2][H2]2

b. Kc=[CO][H2]/[H2O]

16.13

200

true or false: Qc= [products]/[reactants]

true

16.28

200

At  850^oC , the equilibrium constant, Kp, for the reaction C(s)+CO2(g) ->^2 2CO(g) has a value of 10.7. If the total pressure in the system at equilibrium is 1.000 atm, what is the partial pressure of carbon monoxide at equilibrium?

0.921 atm

16.65

200

Consider: 2A(g)+B(g) -> 2C(g)

If  triangleG^o =50.0 kJ/mol at T= 25^oC and Pa=Pb=1 atm and Pc=2 atm, what is the value of  triangleG ? (R=8.314 J/Kmol)

53.4 kJ/mol

16.72

200

Which of the following are considered forms of stress on a system?

a. the addition of a reactant or product

b. the removal of a reactant or product

c. a change in volume of the system, resulting in a change in concentration or partial pressure of the reactants and products

d. a temperature change

e. all of the above

f. a, c, d only

letter e

16.83

300

a. At equilibrium, Qc ? Kc

b. At non-equilibrium, Qc ? Kc

a. =

b. does not =

16.05

300

Answer the question based on the decomposition reaction of carbon dioxide:

3H2(g)+N2(g) ->^2 2NH3(g)

 triangleH=-92.0kJ 

a. increase pressure and the equilibrium shifts...

right 

review sheet, question 10

300

Consider the reaction below. A reaction mixture initially contains 2.0 M SO2 and some solid Cu. Determine the equilibrium concentration of SO2 if Kc for the reaction is 4.0.

Cu(s)+SO2(g) ->^2 CuS(s)+O2(g)

0.4 M

review sheet, question 9

300

Write the equilibrium expression for each:

a. CaCO3(s) ->^2 CaO(s)+CO2(g)

b. Hg(l)+Hg2+(aq) ->^2 Hg22+(aq)

c. 2Fe(s)+3H2O(l) ->^2 Fe2O3(s)+2H2(g)

a. Kc=[CO2]

b. Kc=[Hg22+]/[Hg2+]

c. Kc=[H2]2

16.13

300

How would you write this in Qc form:

N2(g)+3H2(g) ->^2 2NH3(g) 

 ([NH_3 ]^2)/([N_2][H_2]^3) 

16.30

300

The equilibrium constant Kp for the following reaction is 0.0025 at  2127^oC . If a container is charged with 8.00 atm of nitrogen and 5.00 atm of oxygen and the mixture is allowed to reach equilibrium, what will be the equilibrium partial pressure of nitrogen?

N2(g)+O2(g) ->^2 2NO(g)

7.85 atm

16.63

300

H2(g)+I2(g) ->^2 2HI(g)

 triangleG^o at 25^oC=2.60(kJ)/(mol) 

If PH2=2.0 atm; PI2=2.0 atm; and PHI=3.0 atm

What is  triangleG ? Is it spontaneous or non spontaneous?

4.60 kJ/mol

nonspontaneous

16.73

300

a. When a substance is added, the equilibrium shifts to decrease it by using it.

The reaction will shift ____ (from) the side you are adding to.

b. When a substance is removed, the equilibrium shifts to increase it by using it.

The reaction will shift ____ (from) the side you are removing from.

a. away

b. towards

16.84

400

Kc is known as the...

Qc is known as the...

equilibrium constant

reaction quotient

16.04-05

400

Answer the question based on the decomposition reaction of carbon dioxide:

3H2(g)+N2(g) ->^2 2NH3(g)

 triangleH=-92.0kJ 

a. increase temperature and the amount of Hwill...

increase

review sheet, question 10

400

N2O4 decomposes to NO2. The equilibrium constant in the gas phase is 0.36 at  100^oC .

If a 1.00 L flask initially contains 0.100 M N2O4, what will be the equilibrium concentration of NO2?

0.12 M

16.55-57

400

Consider the equilibrium N2(g)+3H2(g) ->^2 2NH3(g) at a certain temperature. An equilibrium mixture in an 8.00 L vessel contains 1.60 mol NH3, 0.800 mol N2, and 1.20 mol H2. What is the value of Kc?

119

16.10

400

Calculate the Reaction Quotient, Q, when 1.00 mol of HF(g), 0.371 mol of H2(g), and 0.750 mol of F2(g) are mixed in a 5.00 L flask.

2HF(g) ->^2 H2(g)+F2(g)

Kc1.00*10^-2 

Q=0.278

review sheet, question 4.a

400

Suppose 15.00 g of solid ammonium hydrogen sulfide is introduced into a 500. mL flask at  25^oC , the flask is sealed, and the system is allowed to reach equilibrium. What is the partial pressure of ammonia in this flask if Kp=0.108 at  25^oC for the following reaction?

NH4HS(g) ->^2 NH3(g)+H2S(g)

0.329 atm

16.66

400

H2(g)+I2(g) ->^2 2HI(g)

 triangleG^o at 25^oC=2.60(kJ)/(mol) 

If PH2=2.0 atm; PI2=2.0 atm; and PHI=1.0 atm

What is  triangleG ? Is it spontaneous or non spontaneous?

-0.8 kJ/mol

spontaneous

16.74

400

H2S is a contaminant commonly found in natural gas. It is removed by reaction with oxygen to produce elemental sulfur.

2H2S(g)+O2(g) ->^2 2S(s)+2H2O(g)

For each scenario, determine whether the equilibrium will shift right, left, or neither:

1. addition of O2(g)

2. removal of H2S(g)

3. removal of H2O(g)

4. addition of S(s)

1. right

2. left

3. right

4. neither

16.85


500

large Kc=______ favored. Reaction is _____

small Kc=______ favored. Reaction is _____

products, spontaneous

reactants, non-spontaneous

16.27

500

Answer the question based on the decomposition reaction of carbon dioxide:

3H2(g)+N2(g) ->^2 2NH3(g)

 triangleH=-92.0kJ 

a. add NH3 and the temperature of the system will...

decrease 

review sheet, question 10

500

For the following reaction, 3.000 mol of each species is put in a 1.500 L vessel. Calculate the equilibrium concentration of each species.

H2(g)+F2(g) ->^2 2HF(g)

Kc1.15*10^2 

[H2]=[F2] 0.47 M

[HF]= 5.06 M

16.58-60

500

What is Kc and Kp for the following expression: 

N2O4(g) ->^2 2NO2(g)

Kc= [NO2]2/[N2O4]

Kp=  (P^2NO_2)/(PN_2O_4) 

16.14

500

A container is filled with 0.83 M ammonia, 0.35 M oxygen, 0.65 M nitrogen, and 1.34 M water vapor at a temperature of  300^oC . Calculate the reaction quotient and state whether the reaction will proceed in the forward or reverse direction. 

4NH3(g)+3O2(g) ->^2 2N2(g)+6H2O(g)

Kc=12.11

Qc=120

120>12.11

Qc>Kc

the reaction will proceed in the reverse direction

review sheet, question 5

500

Consider the following reaction. A reaction mixture initially contains 0.56 atm CO2 and 0.32 atm CO. Determine the total pressure in the container once equilibrium is reached. Kp for the reaction at this temperature is 2.25.

CO2(g)+C(graphite) ->^2 2CO(g)

1.14 atm

review sheet, question 8

500

What belongs in the white box labeled "1."

 triangleG^o is positive

16.76

500

8CO(g)+17H2(g) ->^2 C8H18(g)+8H2O(g)

Suppose the reaction is at equilibrium at 200oC, then is suddenly cooled to condense the octane (C8H18), and then the remaining gases are reheated to 200oC. In which direction will the equilibrium shift?

right

15.86

600

true or false: When both sides of the equilibrium reaction have the same number of moles of gas, pressure has an increasing effect on equilibrium, according to Le Châtelier's Principle.

false, pressure has no effect on the equilibrium 

16.88

600

Answer the question based on the decomposition reaction of carbon dioxide:

3H2(g)+N2(g) ->^2 2NH3(g)

 triangleH=-92.0kJ 

a. remove NH3 and the system will shift...

right


600

Pure NO2 is placed in a vessel and the temperature is brought to 200 K, where the equilibrium constant, Kc, is 0.0015. At equilibrium, the concentration of NO was measured to 0.0800 M. Determine the equilibrium concentration of NO2.

2NO2(g) ->^2 2NO(g)
+O2(g)

0.413 M NO2

review sheet, question 6

600

The value of Kc at 227^oC is 0.0952 for the following reaction:

CH3OH(g) ->^2 CO(g)+2H2(g)

What is Kp at the temperature?

Kp=160.

16.16

600

2NH3(g) ->^2 N2(g)+3H2(g)  

A 50.0 L vessel contains 1.00 mol N2, 3.00 mol H2, and 0.500 mol NH3. In which direction (toward reactants or toward products) will the system shift to reestablish equilibrium at 400oC?

Kc for the reaction at 400oC is 2.00

0.043

Qc<Kc so it proceeds towards products

16.31

600

A mixture of 5.75 atm of H2 and 5.75 atm of I2 is contained in a 1.0 L vessel at  430^oC . The equilibrium constant (Kp) for the reaction at this temperature is 54.3. Determine the equilibrium partial pressures of H2,I2, and HI.

PH2=P12=1.23 atm, PHI=9.04 atm

16.61

600

-3.1 kJ/mol

spontaneous

16.77

600

In which direction will the equilibrium shift when the pressure is increased?

8CO(g)+17H2(g) ->^2 C8H18(g)+8H2O(g)

right

16.91