Question

Which one is the strongest electrolyte among the following?

• A. HF
• B. NH\(_3\)
• C. CaCl\(_2\)
• D. AgCl

Hint:

Soluble ionic salts such as NaCl, KCl, and CaCl$_2$ are strong electrolytes because they dissociate almost completely into ions in aqueous solution.

Answer 1

The Correct Option is C

Concept: Electrolytes are substances that produce ions when dissolved in water and therefore conduct electricity. Electrolytes are classified into:
• Strong electrolytes
• Weak electrolytes Strong electrolytes undergo nearly complete ionization in aqueous solution, whereas weak electrolytes ionize only partially.

Step 1: Examine HF. Hydrofluoric acid is a weak acid. Therefore it ionizes only partially in water. \[ HF \rightleftharpoons H^+ + F^- \] Hence HF is a weak electrolyte.

Step 2: Examine NH\(_3\). Ammonia is a weak base. It undergoes only partial ionization. \[ NH_3+H_2O \rightleftharpoons NH_4^+ + OH^- \] Thus NH\(_3\) is also a weak electrolyte.

Step 3: Examine AgCl and CaCl\(_2\). AgCl is sparingly soluble in water and therefore contributes very few ions. On the other hand, \[ CaCl_2 \rightarrow Ca^{2+}+2Cl^- \] undergoes almost complete dissociation in water. Since it produces a large number of ions, it behaves as a strong electrolyte. Therefore, \[ \boxed{CaCl_2} \] is the strongest electrolyte among the given substances. Hence the correct option is \[ \boxed{(3)} \]