Question

please answear each question

1)At equilibrium, ________.
a)the rates of the forward and reverse reactions are equal
b)the value of the equilibrium constant is 1
c)all chemical reactions have ceased
d)the rate constants of the forward and reverse reactions are equal
e)the limiting reagent has been consumed

2)The equilibrium-constant expression depends on the ________ of the reaction.

a)

stoichiometry

b)

mechanism

c)

the quantities of reactants and products initially present

d)

temperature

e)

stoichiometry and mechanism

3)Given the following reaction at equilibrium, if Kc = 1.90 × 10¹⁹ at 25.0 °C, Kp = ________.

H_{2 (g)} + Br_{2 (g)}  ⇌  2 HBr _(g)

		1.56 x 104
		9.50 x 1018
		6.44 x 105
		5.26 x 10-20
		1.90 x 1019

4)

The Keq for the equilibrium below is 7.52 × 10^-2 at 480.0 °C.

2Cl_{2 (g)} + 2H₂O _(g)  ⇌  4HCl _(g) + O_{2 (g)}

What is the value of Keq at this temperature for the following reaction?

2HCl _(g) + 1/2 O_{2 (g)}  ⇌  Cl_{2 (g)} + H₂O _(g)

3.65

5.66 x 10^-3

13.3

-0.0376

0.274

5) The equilibrium constant for the gas phase reaction

H_{2 (g)} + I_{2 (g)}  ⇌  2HI _(g)

is Keq = 50 at 300 °C. At equilibrium, ________.

products predominate

roughly equal amounts of products and reactants are present

only reactants are present

only products are present

reactants predominate

6)

)At 400 K, the equilibrium constant for the reaction

Br_{2 (g)} + Cl_{2 (g)}  ⇌  2BrCl _(g)

is Kp = 7.0. A closed vessel at 400 K is charged with 1.00 atm of Br_{2 (g)}, 1.00 atm of Cl_{2 (g)}, and 2.00 atm of BrCl (g). Use Q to determine which of the statements below is true.

The equilibrium partial pressures of Br₂, Cl₂, and BrCl will be the same as the initial values.

The reaction will go to completion since there are equal amounts of Br₂ and Cl₂.

At equilibrium, the total pressure in the vessel will be less than the initial total pressure.

The equilibrium partial pressure of Br₂ will be greater than 1.00 atm.

The equilibrium partial pressure of BrCl _(g) will be 4.00 atm.

7) Which reaction will shift to the left in response to a decrease in volume?

4 Fe _(s) + 3 O_{2 (g)}  ⇌  2 Fe₂O_{3 (s)}

N_{2 (g)} + 3H_{2 (g)}  ⇌  2 NH_{3 (g)}

H_{2 (g)} + Cl_{2 (g)}  ⇌  2 HCl _(g)

2 SO_{3 (g)} ⇌  2 SO_{2 (g)} + O_{2 (g)}

2HI _(g)  ⇌  H_{2 (g)} + I_{2 (g)}

8)Consider the following reaction at equilibrium:

2NH_{3 (g)}  ⇌  N_{2 (g)} + 3H_{2 (g)}

Le Châtelier's principle predicts that the moles of H₂ in the reaction container will increase with ________.

a decrease in the total pressure (T constant)

a decrease in the total volume of the reaction vessel (T constant)

addition of some N₂ to the reaction vessel (V and T constant)

some removal of NH₃ from the reaction vessel (V and T constant)

an increase in total pressure by the addition of helium gas (V and T constant)

9)

Consider the following reaction at equilibrium:

2CO_{2 (g)} ⇌ 2CO _(g) + O_{2 (g)} ΔH° = -514 kJ

Le Châtelier's principle predicts that a decrease in temperature will ________.

decrease the partial pressure of O_{2 (g)}

decrease the value of the equilibrium constant

increase the partial pressure of CO_{2 (g)}

decrease the partial pressure of CO

increase the value of the equilibrium constant

10) The effect of a catalyst on an equilibrium is to ________.

increase the equilibrium constant so that products are favored

slow the reverse reaction only

shift the equilibrium to the right

increase the rate of the forward reaction only

increase the rate at which equilibrium is achieved without changing the composition of the equilibrium mixture

11) Consider the following chemical reaction:

CO (g) + 2H_2(g)  ⇌  CH₃OH_(g)

At equilibrium in a particular experiment, the concentrations of CO and H₂ were 0.15 M and 0.36 M respectively. What is the equilibrium concentration of CH3OH? The value of Keq for this reaction is 14.5 at the temperature of the experiment.

12)) A reaction vessel is charged with hydrogen iodide, which partially decomposes to molecular hydrogen and iodine:

2HI _(g)  ⇌  H_2(g) + I_2(g)

When the system comes to equilibrium at 425 °C the partial pressure of HI is 0.708 atm, and the partial pressures of H₂ and I₂ are both 0.0960 atm. The value of Kp at this temperature is ________.

54.3

1.84 x 10^-2

1.3 x 10^-2

Kp cannot be calculated for this gas reaction when the volume of the reaction vessel is not given.

6.8 x 10^-2

13) A sealed 1.0 L flask is charged with 0.500 mol of I₂ and 0.500 mol of Br₂. An equilibrium reaction ensues:

I_{2 (g)} + Br_{2 (g)}  ⇌  2IBr _(g)

When the container contents achieve equilibrium, the flask contains 0.84 mol of IBr. The value of K_eq is ________.

14))The equilibrium constant (Kp) for the interconversion of PCl₅ and PCl₃ is 0.0121. A vessel is charged with PCl₅giving an initial pressure of 0.123 atm and yields PCl₃ and Cl₂. At equilibrium, the partial pressure of PCl3 is ________ atm.

0.123

0.0330

0.0455

0.0782

0.0908

15)   Carbon monoxide and chlorine gas react to produce COCl₂ gas. The K_p for the reaction is 1.49 × 10⁸ at 100.0 °C: In an equilibrium mixture of the three gases, P_CO = P_Cl2 = 7.70 × 10-4 atm. The partial pressure of the product, phosgene ( COCl₂ ), is ________ atm.

2.51 × 10¹⁴

1.92 × 10¹¹

1.15 × 10⁵

3.98 × 10^-15

8.83 × 10¹

16) K_p = 0.0198 at 721 K for the reaction

2HI _(g)  ⇌   H_2(g) + I_2(g)

In a particular experiment, the partial pressures of H₂ and I₂ at equilibrium are 0.678 and 0.788 atm, respectively. The partial pressure of HI is ________ atm.

17))  For the endothermic reaction

CaCO_{3 (s)}  ⇌  CaO _(s) + CO_{2 (g)}

Le Châtelier's principle predicts that ________ will result in an increase in the number of moles of CO₂.

increasing the temperature

decreasing the temperature

increasing the pressure

removing some of the CaCO₃

None of the above

18) For the reaction:

CH_{4 (g)} + 2 H₂O _(g)  ⇌  CO_{2 (g)} + 4 H_{2 (g)}    ΔH = +190 kJ

When CH₄ is added :

the reactions shifts to the right

ΔH increases

there is no change

K_eq decreases

the reaction shifts to the left

19)The equilibrium constant K_c for the formation of nitrosyl chlorine from nitric acid and molecular chlorine is 6.5 x 10⁴at 35°C. In a certain experiment, 2.0 x 10^-2 moles of NO, 8.3 x 10^-3 moles of Cl₂ and 7.2 moles of NOCl are mixed in a 5.0 L flask and are allowed to reach equilibrium.

2NO_(g) + Cl_2(g)   ⇌   2NOCl_(g)

What is Q_c for this reaction? In which direction must the system proceed to reach equilibrium?

		1.7 x 10-4, To the left
		7.8 x 107 , To the left
		1.7 x 10-4, To the right
		4.3 x 104 , To the left
		4.3 x 104 , To the right
		7.8 x 107 , To the right 20)) At elevated temperatures, molecular hydrogen and molecular bromine react to partially form hydrogen bromide: H2 (g) + Br2 (g)  ⇌  2HBr (g) A mixture of 0.682 mol of H2 and 0.440 mol of Br2 is combined in a reaction vessel with a volume of 2.00 L. At equilibrium at 700 K, there are 0.546 mol of H2 present. At equilibrium, there are ________ mol of Br2 present in the reaction vessel.

Answer 1