The enthalpy change for the dissolution of NH₄NO₃ is +26 kJ mol^–1 at 25 °C. Which statement about this reaction is correct?

A. The reaction is exothermic and the solubility decreases at higher temperature.

B. The reaction is exothermic and the solubility increases at higher temperature.

C. The reaction is endothermic and the solubility decreases at higher temperature.

D. The reaction is endothermic and the solubility increases at higher temperature.

D

Sulfur dioxide reacts with oxygen to form sulfur trioxide.

2SO₂ (g) + O₂ (g) $\rightleftharpoons$ 2SO₃ (g)           ΔH = −197 kJ

Which change increases the value of K_c?

A.  increasing the temperature

B.  decreasing the temperature

C.  decreasing [SO₂ (g)]

D.  decreasing [SO₃ (g)]

B

What is the effect of increasing the temperature in this reaction?

CO₂(g) + H₂O(l) $\rightleftharpoons$ H⁺(aq) + HCO₃⁻(aq)     ΔH < 0

A.     The pH will decrease.

B.     The pH will increase.

C.     CO₂ pressure will decrease.

D.     The equilibrium position will shift to the right.

B

What occurs when the pressure on the given equilibrium is increased at constant temperature?

N₂(g) + O₂(g) $\rightleftharpoons$ 2NO(g)     ΔH = +180 kJ

A.     K_c increases and the position of equilibrium moves to the right.

B.     K_c stays the same and the position of equilibrium is unchanged.

C.     K_c stays the same and the position of equilibrium moves to the left.

D.     K_c decreases and the position of equilibrium moves to the left.

B

What is correct for pure hot water?

B

A reversible reaction has a reaction quotient, Q, of 4.5 and equilibrium constant, K_c, of 6.2.

2A (g) $\rightleftharpoons$ A₂(g)

Which statement describes the reaction at this time?

A.  The system has reached equilibrium.

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

C.  The concentration of reactant is greater than the concentration of product.

D.  At equilibrium, the concentration of reactant is greater than the concentration of product.

B

Which variable affects the equilibrium constant, K_c?

A.     Atmospheric pressure

B.     Catalyst

C.     Concentration of reactants

D.     Temperature

D