Question

Be sure to answer all parts. Predict the effect of decreasing the temperature on the amounts of reactants in the following reactions: (a) C2H2(g) + H2O(g) ⇌ CH3CHO(g) ΔH o rxn = −151 kJ The amounts of reactants stay the same. The amounts of reactants decrease. The amounts of reactants increase. (b) CH3CH2OH(l) + O2 (g) ⇌ CH3CO2H(l) + H2O(g) ΔH o rxn = −451 kJ The amounts of reactants stay the same. The amounts of reactants decrease. The amounts of reactants increase. (c) 2 C2H4(g) + O2(g) ⇌ 2 CH3CHO(g) (exothermic) The amounts of reactants stay the same. The amounts of reactants decrease. The amounts of reactants increase. (d) N2O4(g) ⇌ 2 NO2(g) (endothermic) The amounts of reactants decrease. The amounts of reactants stay the same. The amounts of reactants increase.

Answer 1

(a) The amounts of reactants decrease.

(b) The amounts of reactants decrease.

(c) The amounts of reactants decrease.

(d) the amounts of reactants increase.

Step-by-step explanation:

• Le Châtelier's principle states that when there is an dynamic equilibrium, and this equilibrium is disturbed by an external factor, the equilibrium will be shifted in the direction that can cancel the effect of the external factor to reattain the equilibrium.

(a) C₂H₂(g) + H₂O(g) ⇌ CH₃CHO(g) ΔH°rxn = − 151 kJ.

• Since, ΔH is a negative value, the reaction is exothermic reaction.

So, the reaction can be represented as:

C₂H₂(g) + H₂O(g) ⇌ CH₃CHO(g) + heat.

As the temperature is decreases, it is like that decreasing the concentration of products side, that shifts the reaction towards the right side (products side) to attain the equilibrium again. So, the amounts of reactants decrease.

So, the right choice is reaction is: The amounts of reactants decrease.

(b) CH₃CH₂OH(l) + O₂ (g) ⇌ CH₃CO₂H(l) + H₂O(g) ΔH°rxn = − 451 kJ.

• Since, ΔH is a negative value, the reaction is exothermic reaction.

So, the reaction can be represented as:

CH₃CH₂OH(l) + O₂ (g) ⇌ CH₃CO₂H(l) + H₂O(g) + heat.

As the temperature is decreases, it is like that decreasing the concentration of products side, that shifts the reaction towards the right side (products side) to attain the equilibrium again. So, the amount of reactants decrease.

So, the right choice is reaction is: The amounts of reactants decrease.

(c) 2C₂H₄(g) + O₂(g) ⇌ 2CH₃CHO(g) (exothermic).

• Since, the reaction is exothermic reaction.

So, the reaction can be represented as:

2C₂H₄(g) + O₂(g) ⇌ 2CH₃CHO(g) + heat.

As the temperature is decreases, it is like that decreasing the concentration of products side, that shifts the reaction towards the right side (products side) to attain the equilibrium again. So, the amounts of reactants decrease.

So, the right choice is reaction is: The amounts of reactants decrease.

(d) N₂O₄(g) ⇌ 2NO₂(g) (endothermic).

• For endothermic reaction, it can be represented as:

N₂O₄(g) + heat ⇌ 2NO₂(g)

As the temperature is decreased, it is like that decreasing the concentration of reactants side, that shifts the reaction towards the lift side (reactants side) to attain the equilibrium again. So, the amounts of reactants increase.

So, the right choice is reaction is: the amounts of reactants increase.