13.3 Shifting equilibria: le châtelier’s principle  (Page 6/10)

The following equation represents a reversible decomposition:
${\text{CaCO}}_3(s)\rightleftharpoons \text{CaO}(s)+{\text{CO}}_2(g)$

Under what conditions will decomposition in a closed container proceed to completion so that no CaCO ₃ remains?

Explain how to recognize the conditions under which changes in pressure would affect systems at equilibrium.

What property of a reaction can we use to predict the effect of a change in temperature on the value of an equilibrium constant?

What would happen to the color of the solution in part (b) of [link] if a small amount of NaOH were added and Fe(OH) ₃ precipitated? Explain your answer.

The following reaction occurs when a burner on a gas stove is lit:
${\text{CH}}_4(g)+2{\text{O}}_2(g)\rightleftharpoons {\text{CO}}_2(g)+2{\text{H}}_2\text{O}(g)$

Is an equilibrium among CH ₄ , O ₂ , CO ₂ , and H ₂ O established under these conditions? Explain your answer.

A necessary step in the manufacture of sulfuric acid is the formation of sulfur trioxide, SO ₃ , from sulfur dioxide, SO ₂ , and oxygen, O ₂ , shown here. At high temperatures, the rate of formation of SO ₃ is higher, but the equilibrium amount (concentration or partial pressure) of SO ₃ is lower than it would be at lower temperatures.
$2{\text{SO}}_2(g)+{\text{O}}_2(g)⟶2{\text{SO}}_3(g)$

(a) Does the equilibrium constant for the reaction increase, decrease, or remain about the same as the temperature increases?

(b) Is the reaction endothermic or exothermic?

Suggest four ways in which the concentration of hydrazine, N ₂ H ₄ , could be increased in an equilibrium described by the following equation:
${\text{N}}_2(g)+2{\text{H}}_2(g)\rightleftharpoons {\text{N}}_2{\text{H}}_4(g)\text{Δ}H=95\text{kJ}$

Suggest four ways in which the concentration of PH ₃ could be increased in an equilibrium described by the following equation:
${\text{P}}_4(g)+6{\text{H}}_2(g)\rightleftharpoons 4{\text{PH}}_3(g)\text{Δ}H=110.5\text{kJ}$

How will an increase in temperature affect each of the following equilibria? How will a decrease in the volume of the reaction vessel affect each?

(a) $2{\text{NH}}_3(g)\rightleftharpoons {\text{N}}_2(g)+3{\text{H}}_2(g)\text{Δ}H=92\text{kJ}$

(b) ${\text{N}}_2(g)+{\text{O}}_2(g)\rightleftharpoons 2\text{NO}(g)\text{Δ}H=181\text{kJ}$

(c) $2{\text{O}}_3(g)\rightleftharpoons 3{\text{O}}_2(g)\text{Δ}H=\mathrm{-285}\text{kJ}$

(d) $\text{CaO}(s)+{\text{CO}}_2(g)\rightleftharpoons {\text{CaCO}}_3(s)\text{Δ}H=\mathrm{-176}\text{kJ}$