Question

Equivalent weight of a salt depends on _________.

• A. No. of equivalent weight of an acid that combine into salt
• B. Basicity
• C. Acidity
• D. Weight of oxygen

Hint:

To quickly calculate the equivalent weight of any simple salt, divide its molecular weight by the total charge of its cation or anion (e.g., for $\text{Al}_2(\text{SO}_4)_3$, the total cation charge is $2 \times (+3) = 6$, so equivalent weight is $\text{M}/6$).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The equivalent weight of a substance is the mass that combines with or displaces a fixed amount of a reference substance (such as $1.008 \text{ g}$ of hydrogen or $8.0 \text{ g}$ of oxygen).
For a salt, equivalent weight is determined by its neutralization reaction.

Step 2: Key Formula or Approach:
The equivalent weight of a salt is generally calculated as:
\[ \text{Equivalent Weight of Salt} = \frac{\text{Formula Weight (Molecular Weight) of Salt}}{\text{Total Positive or Negative Valency}} \]

Step 3: Detailed Explanation:
A salt is produced by the neutralization reaction between an acid and a base.
According to the law of equivalence, one equivalent of an acid reacts with exactly one equivalent of a base to produce one equivalent of a salt.
Therefore, the equivalent weight of a salt is directly related to the number of equivalents of the acid (or base) that combine to form the salt.
For example, in the formation of calcium sulfate ($\text{CaSO}_4$):
One mole of sulfuric acid ($\text{H}_2\text{SO}_4$, which has a basicity of 2 and contains 2 equivalents of acid) reacts with one mole of calcium hydroxide ($\text{Ca(OH)}_2$) to form one mole of calcium sulfate.
Because 2 equivalents of acid combined to form the salt, the equivalent weight of the resulting $\text{CaSO}_4$ is its molecular weight divided by 2.
While the equivalent weight of an acid depends on its basicity (B) and that of a base depends on its acidity (C), the equivalent weight of the resulting salt is determined by the number of equivalents of acid that combined to form it.

Step 4: Final Answer:
The equivalent weight of a salt depends on the number of equivalent weights of acid that combine to form the salt, corresponding to option (A).