Question

unit 3 practice #2
26.
the diagram above represents a solution of ions in water. which of the following are the most likely identities of ions x and y?
(a) ion x is na+, and ion y is k+.
(b) ion x is na+, and ion y is f−.
(c) ion x is cl−, and ion y is k+.
(d) ion x is cl−, and ion y is f−.

1. of the three solutions listed in the table, which one, if any, has the greatest electrical conductivity and why?

(a) 0.1 m hc2h3o2(aq) because its molecules have the most atoms.
(b) 0.1 m ki(aq) because ki completely dissociates in water to produce ions.
(c) 0.1 m ch3oh(aq) because its molecules can form hydrogen bonds.
(d) all three solutions have the same electrical conductivity because the concentrations are the same.

Explanation:

Step1: Analyze the nature of each substance

• \(HC_{2}H_{3}O_{2}(aq)\) (acetic acid) is a weak acid. It partially dissociates in water (\(HC_{2}H_{3}O_{2}

ightleftharpoons H^{+}+C_{2}H_{3}O_{2}^{-}\)), so it produces a relatively small number of ions.

• \(KI(aq)\) is a strong electrolyte. It completely dissociates in water (\(KI = K^{+}+I^{-}\)), producing a large number of ions.
• \(CH_{3}OH(aq)\) (methanol) is a non - electrolyte. It does not dissociate into ions in water.

Step2: Relate ion concentration to electrical conductivity

Electrical conductivity of an aqueous solution is due to the presence of ions. The more ions in solution, the higher the electrical conductivity. Since \(KI\) completely dissociates and \(HC_{2}H_{3}O_{2}\) partially dissociates and \(CH_{3}OH\) does not dissociate, the solution of \(KI\) has the highest ion concentration.

Answer:

B. \(0.1\ M\ KI(aq)\) because \(KI\) completely dissociates in water to produce ions.