Question

How to prepare n/20 naoh solution in 250 ml of water?

Answer 1

Answer:

by adding 0.5 gm of naoh

Explanation:

1/20=mass of naoh/equivalent mass of naoh ×1000/250

Answer 2

The mass of solid NaOH required is 0.5 g

Explanation:

Equivalent weight is calculated by dividing the molecular weight by n factor. The equation used is:

$\text{Equivalent weight}=\frac{\text{Molecular weight}}{n}$

where,

n = acidity for bases = 1 (For NaOH)

Molar mass of NaOH = 40 g/mol

Putting values in above equation, we get:

$\text{Equivalent weight}=\frac{40g/mol}{1eq/mol}=40g/eq$

Normality is defined as the umber of gram equivalents dissolved per liter of the solution.

Mathematically,

$\text{Normality of solution}=\frac{\text{Number of gram equivalents} \times 1000}{\text{Volume of solution (in mL)}}$

Or,

$\text{Normality of solution}=\frac{\text{Given mass}\times 1000}{\text{Equivalent mass}\times \text{Volume of solution (in mL)}}$    ......(1)

We are given:

Given mass of NaOH = ?

Equivalent mass of NaOH = 40 g/eq

Volume of solution = 250 mL

Normality of solution = $\frac{N}{20}=0.05eq/L$

Putting values in equation 1, we get:

$0.05eq/L=\frac{\text{Mass of NaOH}\times 1000}{40g/eq\times 250mL}\\\\\text{Mass of NaOH}=\frac{0.05\times 40\times 250}{1000}=0.5g$

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