Predict whether the following compounds are a strong electrolyte, weak electrolyte, or nonelectrolyte: (a) KBr, (b) NaI, (c) C3H7OH.
The correct answer and explanation is:
Electrolytes are substances that, when dissolved in water, dissociate into ions and thus conduct electricity. They can be classified as strong electrolytes, weak electrolytes, or nonelectrolytes based on their ability to dissociate.
(a) KBr (Potassium bromide)
Strong electrolyte
KBr is an ionic compound consisting of potassium ions (K⁺) and bromide ions (Br⁻). In water, ionic compounds dissociate completely into their constituent ions, making them strong electrolytes. When KBr is dissolved in water, it dissociates completely: KBr→K++Br−\text{KBr} \rightarrow \text{K}^+ + \text{Br}^- This complete dissociation results in a large number of free ions in the solution, allowing the solution to conduct electricity very efficiently. Therefore, KBr is classified as a strong electrolyte.
(b) NaI (Sodium iodide)
Strong electrolyte
NaI is also an ionic compound composed of sodium ions (Na⁺) and iodide ions (I⁻). Similar to KBr, NaI dissociates completely into its ions when dissolved in water: NaI→Na++I−\text{NaI} \rightarrow \text{Na}^+ + \text{I}^- Since NaI is a strong electrolyte, it also dissociates completely in aqueous solution, leading to the formation of free ions that conduct electricity effectively. This behavior is characteristic of a strong electrolyte.
(c) C₃H₇OH (Propanol)
Nonelectrolyte
Propanol (C₃H₇OH) is an alcohol that contains a hydroxyl group (-OH). Alcohols like propanol do not dissociate into ions in water. Instead, they form hydrogen bonds with water molecules, but they remain in molecular form. As propanol does not produce free ions in solution, it does not conduct electricity. Therefore, C₃H₇OH is classified as a nonelectrolyte.
Conclusion:
- KBr: Strong electrolyte (complete dissociation into ions).
- NaI: Strong electrolyte (complete dissociation into ions).
- C₃H₇OH: Nonelectrolyte (does not dissociate into ions in solution).