Q: Given the reactions: $$HA \rightleftharpoons H^+ + A^-$$ with $$K_1$$ $$HA + C^+ \rightleftharpoons H^+ + AC^+$$ with $$K_2$$ What is the equilibrium constant for the sum of these reactions?

$$K_3$$ = $$K_1$$ \times $$K_2$$

Question 1

For the reaction $$aA + bB \rightleftharpoons cC + dD$$, which of the following correctly expresses the equilibrium constant $$K$$?

Accepted Answer

$$K = \dfrac{[C]^c[D]^d}{[A]^a[B]^b}$$

Question 2

If the equilibrium constant $$K$$ for a reaction is greater than 1, what does this indicate about the reaction?

Accepted Answer

The products are favored at equilibrium.

Question 3

Which of the following is omitted from the equilibrium constant expression?

Accepted Answer

Concentration of pure solids and pure liquids

Question 4

If the direction of a chemical reaction is reversed, how is the new equilibrium constant $$K'$$ related to the original $$K$$?

Accepted Answer

$$K' = \dfrac{1}{K}$$

Question 5

Given the reactions: 
$$HA \rightleftharpoons H^+ + A^-$$ with $$K_1$$ 
$$HA + C^+ \rightleftharpoons H^+ + AC^+$$ with $$K_2$$ 
What is the equilibrium constant for the sum of these reactions?

Accepted Answer

$$K_3$$ = $$K_1$$ 	imes $$K_2$$

Question 6

Which of the following best describes the effect of adding two reactions together on their equilibrium constants?

Accepted Answer

The new equilibrium constant is the product of the individual constants.

Question 7

Consider the following reactions and their equilibrium constants:
$$NH_4^+ + OH$$^- ightleftharpoons $$NH_3 + H_2O$ with K_1$ = 5.6 	imes 10$$^{-10}$$
H_2O$$ ightleftharpoons H^+ + OH^-$$ with K_2$ = 1.0 	imes 10$$^{-14}$$
What is the equilibrium constant for the reaction NH_4$^+ ightleftharpoons NH_3$ + H^+$$?

Accepted Answer

$$K = K_1$ 	imes K_2$

Question 8

Which thermodynamic quantity describes the heat absorbed or released during a chemical reaction at constant pressure?

Accepted Answer

Enthalpy ($$\Delta H)$$

Question 9

A reaction has $$\Delta H^\circ = -74.85 kJ/$$mol. What does this indicate about the reaction?

Accepted Answer

The reaction is exothermic and releases heat.

Question 10

Which statement about entropy ($$S) is $$correct?

Accepted Answer

A gas has higher entropy than a solid.

Question 11

For the reaction $$KCl(s) \rightleftharpoons K^+(aq) + Cl^-(aq)$$, the standard entropy change $$\Delta S^\circ is $$positive. What does this imply?

Accepted Answer

The system becomes more disordered.

Question 12

Which of the following is true regarding the standard state of a species in equilibrium calculations?

Accepted Answer

Solutes: 1 M; Gases: 1 bar; Solids and liquids: pure solid or liquid

Question 13

Which of the following best describes the relationship between equilibrium and thermodynamics?

Accepted Answer

Equilibrium is controlled by the thermodynamics of a chemical reaction.

Question 14

If $$K = 1$$ for a reaction, what does this indicate about the relative concentrations of reactants and products at equilibrium?

Accepted Answer

Reactants and products are present in comparable amounts.

Question 15

Which of the following reactions is endothermic?

Accepted Answer

$$\Delta H^\circ = +25 kJ/$$mol$

Question 16

Which of the following is true about the manipulation of equilibrium constants when $$n$$ reactions are added together?

Accepted Answer

The overall equilibrium constant is the product of the individual constants.

Question 17

Which of the following best describes the entropy change when a solid dissolves in water to form ions?

Accepted Answer

Entropy increases because the system becomes more disordered.

Question 18

Which of the following is NOT a factor that independently contributes to the favorability of a chemical reaction at equilibrium?

Accepted Answer

Initial concentration of reactants

Question 19

Which of the following statements is correct regarding the equilibrium constant for the reaction $$HA \rightleftharpoons H^+ + A^-$$?

Accepted Answer

$$K = \dfrac{[H^+][A^-]}{[HA]}$$

Chemical Equilibrium: Principles and Manipulation (Chapter 6 Study Notes)

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