Question

How many of the following are strong electrolytes?
(a) $N{{H}_{3}}$ (b) $N{{H}_{4}}Cl$
(c) $C{{H}_{3}}COOH$ (d) $C{{H}_{3}}COONa$
(e) $HCl$ (f) $NaCl$

Answer 1

The substances or compounds which give ions when dissolved in water are called electrolytes. For a solution to be called an electrolyte, water is the most important solvent.

Complete step by step solution:
-Water is a universal, polar solvent that can dissolve maximum solutes. The solutions in which water is the dissolving medium for solutes are called aqueous solutions.
-The electrolytes are broadly classified as acids, bases or salts depending on the type of ions they produce when dissolved in water.
-Due to the production of electrolytes, positive and negative ions are generated which conducts electricity.
-A solute that dissociates or ionizes completely in a solution is called strong electrolytes. Strong electrolytes are very good conductors of electricity.
-A solute that does not dissociate or ionizes at all or very little amount of it undergoes dissociation are called weak electrolytes. Weak electrolytes do not or conduct negligible electricity.
-The strength of an electrolyte either to be a weak electrolyte or strong electrolyte depends on the substance's ability to form ions by dissociation.
-For a strong electrolyte, a high degree of dissociation is observed in the solution, while for weak electrolytes, a very low degree of dissociation is observed.
-For strong electrolytes, the equilibrium position lies very far to the right and for the weak electrolytes, the equilibrium position lies very far to the left.
-Following are the guidelines to be followed in determining the strength of an electrolyte-
(i) Acids- Most of the acids are weak acids and thus weak electrolytes. Strong acids are strong electrolytes. For example strong acids like $HCl,HN{{O}_{3}},HBr,\text{ and }{{H}_{2}}S{{O}_{4}}$are strong electrolytes and weak acids like $HF,C{{H}_{3}}COOH,\text{ and }{{H}_{2}}C{{O}_{3}}$are weak electrolytes.
(ii) Bases- Strong bases are strong electrolytes and weak bases are weak electrolytes. Strong bases like NaOH, KOH, and LiOH are strong electrolytes and weak bases like ammonia and pyridine are weak electrolytes.
(iii) Salts- If the given compound is in the form $Metal{{(X)}_{n}}$, it is a salt. Most of the salts are strong salts. Weak salts include $HgC{{l}_{2}}\text{ and }CdS{{O}_{4}}$salts.
(iv) Water is a weak electrolyte.
(v) Complex ions are weak electrolytes.
(vi) If the given compound is in the form $Metal{{(OH)}_{n}}$, then it is a strong base, and thus a strong electrolyte.
(vii) If the compound has a nitrogen atom, then it is a weak base and thus a weak electrolyte.
(viii) If the compound has a formula that starts with ‘H’, it is probably a weak acid and thus weak electrolyte.
-Following the above guideline, we can now identify the given compounds as strong electrolytes and weak electrolytes-
$N{{H}_{3}}$(weak electrolyte) ; $N{{H}_{4}}Cl$(strong electrolyte) ; $C{{H}_{3}}COOH$(weak electrolyte) ; $C{{H}_{3}}COONa$
(strong electrolyte) ; $HCl$ ( strong electrolyte) ; $NaCl$ (strong electrolyte).

Note: The hydroxides of Group I (alkali metals) and Group II (alkaline-earth metals) are strong bases and therefore strong electrolytes, except $Ba{{(OH)}_{2}}_{(aq)}$which is a weak electrolyte.