Problem: KBr is relatively soluble in water, yet its enthalpy of solution is +19.8 kJ/mol. Which of the following statements provides the best explanation for this behavior?(a) Potassium salts are always soluble in water.(b) The entropy of mixing must be unfavorable.(c) The enthalpy of mixing must be small compared to the enthalpies for breaking up water–water interactions and K–Br ionic interactions.(d) KBr has a high molar mass compared to other salts like NaCl.

FREE Expert Solution

Interactions in a solution:

solute–solute

solvent–solvent

solute-solvent


(a) Potassium salts are always soluble in water.

→ not a good explanation


(b) The entropy of mixing must be unfavorable.

→ if the entropy of mixing is unfavorable then the KBr will not be soluble


(c) The enthalpy of mixing must be small compared to the enthalpies for breaking up water–water interactions and K–Br ionic interactions.

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Problem Details

KBr is relatively soluble in water, yet its enthalpy of solution is +19.8 kJ/mol. Which of the following statements provides the best explanation for this behavior?
(a) Potassium salts are always soluble in water.
(b) The entropy of mixing must be unfavorable.
(c) The enthalpy of mixing must be small compared to the enthalpies for breaking up water–water interactions and K–Br ionic interactions.
(d) KBr has a high molar mass compared to other salts like NaCl.

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