Problem # 56 Electrical conduction of aqueous solutions [Solved]

You are given two aqueous solutions A and B. The only information you have is that A conducts electricity, B doesn’t.

Question: Which of the two solutions contains potassium bromide (KBr) and which one contains ethanol (CH₃CH₂OH)? Explain/justify your answer.

Answer:

Solution A is KBr(aq) solution; Solution B is CH₃CH₂OH(aq) solution.

Indeed, KBr is an ionic compound formed between a metal (K) and anon-metal (Br₂); when it dissolves in water, it dissociates into its ions K⁺ and Br^-. The presence of ions allows KBr(aq) solution to conduct electricity. Such solutions are called “Electrolytes” or “Electrolytic solutions”. Hence A corresponds to KBr(aq) solution.

CH₃CH₂OH is a covalent compound (made of all non-metals); its dissolution in water does not involve the dissociation into ions. The absence of ions in the aqueous solution of CH₃CH₂OH explains why that solution does not conduct electricity. Such solutions are called “Non-electrolytes” or “Non-electrolytic solutions”. That is why the aqueous solution of ethanol doesn’t conduct electricity.