Respuesta :
Answer: The mass of solid NaOH required is 80 g
Explanation:
Equivalent weight is calculated by dividing the molecular weight by n factor. The equation used is:
[tex]\text{Equivalent weight}=\frac{\text{Molecular weight}}{n}[/tex]
where,
n = acidity for bases = 1 (For NaOH)
Molar mass of NaOH = 40 g/mol
Putting values in above equation, we get:
[tex]\text{Equivalent weight}=\frac{40g/mol}{1eq/mol}=40g/eq[/tex]
Normality is defined as the umber of gram equivalents dissolved per liter of the solution.
Mathematically,
[tex]\text{Normality of solution}=\frac{\text{Number of gram equivalents} \times 1000}{\text{Volume of solution (in mL)}}[/tex]
Or,
[tex]\text{Normality of solution}=\frac{\text{Given mass}\times 1000}{\text{Equivalent mass}\times \text{Volume of solution (in mL)}}[/tex] ......(1)
We are given:
Given mass of NaOH = ?
Equivalent mass of NaOH = 40 g/eq
Volume of solution = 400 mL
Normality of solution = 5 eq/L
Putting values in equation 1, we get:
[tex]5eq/L=\frac{\text{Mass of NaOH}\times 1000}{40g/eq\times 400mL}\\\\\text{Mass of NaOH}=80g[/tex]
Hence, the mass of solid NaOH required is 80 g
