Chapter 15: Problem 64

For a certain gas-phase reaction, the fraction of products in an equilibrium mixture is increased by either increasing the temperature or by increasing the volume of the reaction vessel. (a) Is the reaction exothermic or endothermic? (b) Does the balanced chemical equation have more molecules on the reactant side or product side?

Short Answer

Expert verified

(a) The reaction is endothermic, as increasing the temperature increases the fraction of products in an equilibrium mixture. (b) The balanced chemical equation has more molecules on the product side, as increasing the volume of the reaction vessel increases the fraction of products.

Step by step solution

When the temperature of a reaction at equilibrium is increased, the reaction will shift in the direction of the reaction that can consume the added energy (heat). If the reaction is exothermic, heat is released, and if it is endothermic, heat is absorbed. As increasing the temperature increases the fraction of products, the reaction must be shifting towards the products, indicating that it is an endothermic reaction. So, the answer to question (a) is endothermic. #Step 2: Determine if there are more molecules on the reactant or product side of the balanced chemical equation#

When the volume of a reaction mixture at equilibrium is increased, the pressure decreases, and the system will shift to the side with more moles of gas. Increasing the volume of the reaction vessel results in an increase in the fraction of products. Therefore, the reaction must be shifting towards the products side, which means the product side has more molecules than the reactant side. Thus, the answer to question (b) is that the balanced chemical equation has more molecules on the product side.