Problem 13 - Chemistry: The Central Science

Question

Indicate whether each statement is true or false: (a) A solute will dissolve in a solvent if solute-solute interactions are stronger than solute-solvent interactions. (b) In making a solution, the enthalpy of mixing is always a positive number. (c) An increase in entropy favors mixing.

Step-by-Step Solution

Answer

(a) False: A solute will not dissolve in a solvent if solute-solute interactions are stronger than solute-solvent interactions. (b) False: The enthalpy of mixing can be positive or negative, depending on the mixing process being endothermic or exothermic. (c) True: An increase in entropy, or disorder, favors the mixing process.

Step 1: Statement 1: Solubility and solute-solvent interactions

In order for a solute to dissolve in a solvent, the interactions between solute and solvent particles must be stronger than the interactions between solute-solute particles. If solute-solute interactions are stronger than solute-solvent interactions, the solute will not dissolve in the solvent. Therefore, statement (a) is false.

Step 2: Statement 2: Enthalpy of mixing

The enthalpy of mixing can either be positive or negative, depending on whether the mixing process is endothermic or exothermic. It's not correct to say that the enthalpy of mixing is always positive. Therefore, statement (b) is false.

Step 3: Statement 3: Entropy and mixing

An increase in entropy means an increase in disorder or randomness in a system. When two substances are mixed together, the disorder of the system usually increases, which is favorable for the mixing process. Therefore, statement (c) is true. To sum up: (a) False (b) False (c) True