Question

Normality of solution 20.5 gm of NaOH solution in 1000 mL of solution is:

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Hint: Normality formula will be almost the same as that of molarity. But we take the number of equivalents for calculating normality whereas we take the number of moles for calculating molarity. Try to figure out what equivalents mean.

For bases equivalent weight = $\frac { molecular\quad weight\quad of\quad base }{ acidity\quad of\quad base }$
The equivalent weight of NaOH = $\frac { molecular\quad weight\quad of\quad NaOH }{ acidity\quad of\quad NaOH } \quad =\quad \frac { 40 }{ 1 } \quad =\quad 40$
Normality of NaOH solution = $\frac { Weight\quad of\quad NaOH }{ equivalent\quad weight\quad of\quad NaOH } \times \frac { 1 }{ volume\quad of\quad solution\quad in\quad liters }$
Normality of NaOH = $\frac { 20.5 }{ 40 } \times \frac { 1 }{ 1 } \quad =\quad \frac { 20.5 }{ 40 } \quad =\quad \frac { 41 }{ 80 } \quad =\quad 0.5125N$