Q. Calculate the molarity and normality of a solution containing 0.5 g of NaOH dissolved in 500 ml. solution-
Solutions
Solution:
Wt. of NaOH dissolved $= 0.5 \,g$
Vol. of NaOH solution = 500 ml
Calculation of molarity
0.5 g of NaOH $=\frac{0.5}{40}$ moles of NaOH
$[\because$ Mol. wt. of NaOH = 40]
= 0.0125 mole
Thus 500 ml of the solution contain NaOH = 0.0125 mole
$\therefore $ 1000 ml of the solution contain
$=\frac{0.0125}{500}\times 1000=0.025\,M$
Hence molarity of the solution = 0.025 M
Calculation of normality
Since NaOH is monoacidic;
Eq. wt. of NaOH = Mol. wt. of NaOH =40
$\therefore $ 0.5 g of NaOH
$=\frac{0.5}{40}\,g$ equivalents = 0.0125 gram equivalents
Thus 500 ml of the solution contain NaOH = 0.0125 g equiv
$\therefore $ 1000 ml of the solution contain
$=\frac{0.0125}{500} \times 1000=0.025$
Hence normality of the solution = 0.025 N
Hence molarity of the solution = 0.025 M
Calculation of normality
Since NaOH is monoacidic;
Eq. wt. of NaOH = Mol. wt. of NaOH =40
$\therefore $ 0.5 g of NaOH
$=\frac{0.5}{40}\,g$ equivalents = 0.0125 gram equivalents
Thus 500 ml of the solution contain NaOH = 0.0125 g equiv
$\therefore $ 1000 ml of the solution contain
$=\frac{0.0125}{500} \times 1000=0.025$
Hence normality of the solution = 0.025 N