How To Calculate Normality
When 1 gm equivalent
solute dissolved in 1000 ml solution it’s called 1 normal or 1 N solution.
Symbol for Normality is
“N”
So we can say that
Normality is amount of solute in equivalent gm dissolved in 1 liter solution.
Be clear that final
volume of solution must be 1 liter.
Normality = (Weight of
solute in gram) / (Equivalent weight of solute × Volume of solution in liter)
So what is equivalent
weight?
For acid equivalent
weight = molecular weight / basicity
For base equivalent
weight = molecular weight / acidity
Acidity or basicity is
nothing but change in oxidation state or electron transfer during the reaction.
For NaOH = 40/1 = 40
equivalent gm
For HCl = 36.5/1 = 36.5
equivalent gm
For H2SO4
= 98/2 = 49 equivalent gm
Suppose you want to
make 1 N NaOH 250 ml solution
For NaOH = 40/1 = 40
equivalent gm
Normality = (Weight of
solute in gram) / (Equivalent weight of solute × Volume of solution in liter)
1 = (Weight of solute
in gram) / (40 × 0.250 lit)
Required weight of NaOH
in gram = 1 × 40 × 0.250 = 10 gm NaOH
So by
using 10 gm NaOH, dissolve in minimum quantity of water and make up to final
volume 250 ml, that solution will be 1 N NaOH 250 ml solution
