Quiz 4: Chemical Equilibrium

Which of the following is correct when a chemical system has reached equilibrium?

• The forward and reverse reactions have stopped.

• The rate of the forward reaction is greater than the rate of the reverse reaction.

• The rate of the forward reaction is less than the rate of the reverse reaction.

• The rate of the forward reaction is equal to the rate of the reverse reaction.

In order to write the equilibrium constant expression for a reaction, you must__________.

• know the rate of the forward and reverse reactions.

• know the concentrations of all reactants and products.

• have the balanced chemical equation for the reaction.

• know the conditions of pressure, temperature, and concentration for the system.

What is the equilibrium constant expression for

CO₂(g) + H₂(g) ⇌ CO(g) + H₂O(l)

• K_eq= [CO][H₂O] / [CO₂][H₂]

• K_eq= [CO₂][H₂] / [CO]

• K_eq= [CO₂][H₂] / [CO][H₂O]

• K_eq= [CO] / [CO₂][H₂]

Consider the following reaction. What would be the equilibrium constant expression?

4Br₂(g) + CH₄(g) ⇌ 4HBr(g) + CBr₄(g)

• K_eq = [Br₂]⁴[CH₄]/ [HBr]⁴[CBr₄]

• K_eq = [HBr]⁴[CBr₄]/ [Br₂]⁴[CH₄]

• K_eq = [HBr ]/ [Br₂]⁴[CH₄]

• K_eq = [HBr]⁴[CBr₄]/ [Br₂]⁴[CH]⁴

Consider the following reaction at a specific temperature:

H₂ (g) + Cl₂ (g) ⇌ 2HCl (g)

If K_eq= 2.3x10^-5, [H₂]= 0.0056 M, and [Cl₂]= 0.0048 M, calculate the concentration of HCl.

- Report your answer with correct significant figures and with the correct units.

- Answers must be typed next to each other, without spaces.

- Using ' * ' for multiplication and using ^ for raised to the power. Example: 1.45*10^-5

Consider the following reaction at a specific temperature:

CO (g) + 3H₂ (g) ⇌ CH₄ (g) + 3H₂O (g)

If [CO] = 4.0 M. [H₂] = 2.8 M, [CH₄] = 0.75 M, and [H₂O] = 0.12M, calculate the value of the equilibrium constant.

- Report your answer with correct significant figures.

- Answers must be typed next to each other, without spaces.

- Using ' * ' for multiplication and using ^ for raised to the power. Example: 1.45*10^-5

What kind of equilibrium does the reaction below show?

H₂ (g) +I₂ (g) ⇌ 2HI (g)

• Heterogeneous equilibrium, all the reactants and products are in the same physical state.

• Heterogeneous equilibrium, the reactants and products are present in more than one physical state.

• Homogeneous equilibrium, all the reactants and products are in the same physical state.

• Homogeneous equilibrium, the reactants and products are present in more than one physical state

For the reaction:

N₂ (g) + O₂ (g) ⇌ 2NO (g)

If O₂ is removed, the reaction will shift to the ____________ and the concentration of N₂ will _________.

• right / increase

• left / increase

• left / decrease

• not shift / remain the same

For the reaction

N₂ (g) + O₂ (g) ⇌ 2NO (g)

If NO is added, the reaction will shift to the ____________and the concentration of N₂ will __________.

• right / increase

• right / decrease

• left / increase

• left / decrease

Which equilibrium constant represents a reaction that is reactant favored?

• K_eq = 4.5 x 10²

• K_eq = 3.8

• K_eq = 8.4 x 10^–5

• K_eq = 6.3 x 10⁵