How many gram of sodium hydroxide pellets containing 12% moisture are required to prepare 60 litre of 0.5N solution.

Explanation

To solve the problem of how many grams of sodium hydroxide (NaOH) pellets containing 12% moisture are required to prepare 60 liters of a 0.5N solution, we can follow these steps:

### Step 1: Calculate the equivalent weight of NaOH
The equivalent weight of NaOH can be calculated as follows:
- Atomic weight of Sodium (Na) = 23 g/mol
- Atomic weight of Oxygen (O) = 16 g/mol
- Atomic weight of Hydrogen (H) = 1 g/mol

So, the molecular weight of NaOH = 23 + 16 + 1 = 40 g/mol.

### Step 2: Determine the mass of NaOH needed for the solution
Since the normality (N) of the solution is given as 0.5N, we can calculate the mass of NaOH required for 60 liters:
- The formula for mass required is:
\[ \text{Mass} = \text{Normality} \times \text{Equivalent weight} \times \text{Volume (in liters)} \]
- Substituting the values:
\[ \text{Mass} = 0.5 \, \text{N} \times 40 \, \text{g/equiv} \times 60 \, \text{L} \]
- Calculating this gives:
\[ \text{Mass} = 0.5 \times 40 \times 60 = 1200 \, \text{grams} \]

### Step 3: Adjust for moisture content
Since the NaOH pellets contain 12% moisture, only 88% of the mass is actually NaOH. Therefore, we need to find the total mass of the pellets required to obtain 1200 grams of NaOH:
- Let \( x \) be the total mass of the NaOH pellets required.
- The equation considering moisture is:
\[ 0.88x = 1200 \]
- Solving for \( x \):
\[ x = \frac{1200}{0.88} \approx 1363.64 \, \text{grams} \]

### Conclusion
To prepare 60 liters of a 0.5N NaOH solution, you will need approximately **1363.64 grams** of sodium hydroxide pellets containing 12% moisture.

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