Q17.71P - Chemistry: Molecular Nature Of Matter And Change

Question

Predict the effect of increasing the temperature on the amounts of products in the following reactions:

(a) ${\mathbf{\text{CO(g)+2H}}}_{\mathbf{\text{2}}}\mathbf{\text{(g)}}\mathbf{\rightleftharpoons }{\mathbf{\text{CH}}}_{\mathbf{\text{3}}}{\mathbf{\text{OH(g)\hspace{1em}ΔH}}}_{\mathbf{\text{rxn}}}^{\mathbf{\text{°}}}\mathbf{\text{=-90.7 kJ}}$ 

(b) ${\mathbf{\text{C(s)+H}}}_{\mathbf{\text{2}}}\mathbf{\text{O(g)}}\mathbf{\rightleftharpoons }{\mathbf{\text{CO(g)+H}}}_{\mathbf{\text{2}}}{\mathbf{\text{(g)\hspace{1em}ΔH}}}_{\mathbf{\text{ran}}}^{\mathbf{\text{°}}}\mathbf{\text{=131 kJ}}$

(c) $\mathbf{2}\mathit{N}{\mathit{O}}_{\mathbf{2}}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\mathbf{ }\mathbf{\rightleftharpoons }\mathbf{ }\mathbf{ }\mathbf{2}\mathit{N}\mathit{O}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\mathbf{+}{\mathit{O}}_{\mathbf{2}}\mathbf{\left(}\mathbf{g}\mathbf{\right)}$ (endothermic)

(d) $\mathbf{2}\mathbf{C}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{+}{\mathbf{O}}_{\mathbf{2}}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\mathbf{ }\mathbf{\rightleftharpoons }\mathbf{ }\mathbf{2}\mathbf{CO}\mathbf{\left(}\mathbf{g}\mathbf{\right)}$ (exothermic)

Step-by-Step Solution

Answer

Answer

(a) The amount of product available decreases. 

(b) The amount of product produced increases.

(c) The amount of product produced increases.

(d) The amount of product available decreases.

Step 1: Definition of Concept

Reactions: A balanced chemical reaction equation shows the mole relationships of reactants and products, while a chemical reaction equation gives the reactants and products. The amount of energy involved in the reaction is frequently stated. Reaction stoichiometry is the study of the quantitative aspects of chemical reactions.

Step 2: Predict the effect of increasing the temperature on the amounts of products

(a)

Considering the given reaction,

${\text{CO(g)+2H}}_{\text{2}}\text{(g)}\rightleftharpoons {\text{CH}}_{\text{3}}{\text{OH(g)\hspace{1em}ΔH}}_{\text{rxn}}^{\text{°}}\text{=-90.7 kJ}$

This is an exothermic reaction.

The equilibrium shifts to the left, bringing the reactants closer together.

Therefore, the amount of product available decreases. 

Step 3: Predict the effect of increasing the temperature on the amounts of products

(b)

Considering the given reaction,

${\text{C(s)+H}}_{\text{2}}\text{O(g)}\rightleftharpoons {\text{CO(g)+H}}_{\text{2}}{\text{(g)\hspace{1em}ΔH}}_{\text{ran}}^{\text{°}}\text{=131 kJ}$

This is an endothermic reaction.

The balance shifts to the right, in favour of the products.

Therefore, the amount of product produced increases.

Step 4: Predict the effect of increasing the temperature on the amounts of products

(c)

Considering the given reaction,

$\mathbf{2}{\mathbf{NO}}_{\mathbf{2}}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\mathbf{ }\mathbf{\rightleftharpoons }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{2}\mathbf{NO}\mathbf{\left(}\mathbf{g}\mathbf{\right)}{\mathbf{O}}_{\mathbf{2}}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\mathbf{\left(}\mathbf{endothermic}\mathbf{\right)}$ 

This is an endothermic reaction.

The balance shifts to the right, in favour of the products.

Therefore, the amount of product produced increases.

Step 5: Predict the effect of increasing the temperature on the amounts of products

(d)

Considering the given reaction,

$\mathbf{2}\mathit{C}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{+}{\mathit{O}}_{\mathbf{2}}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\mathbf{ }\mathbf{\rightleftharpoons }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{2}\mathit{C}\mathit{O}\mathbf{\left(}\mathbf{g}\mathbf{\right)}$(endothermic)

This is an exothermic reaction.

The equilibrium shifts to the left, bringing the reactants closer together.

Therefore, the amount of product available decreases.