0.50 g of an organic compound was Kjeldahlished. The ammonia evolved was passed in `50 cm^(3)` of 1N `H_(2)SO_(4)`. The residual acid required `60 cm^(3)` of `N // 2` NaOH solution. Calculate the percentage of nitrogen in the compound.

Explanation

Step 1. Calculation of volume of unused acid
`"Volume of NaOH solution required" = 60 cm^(3)`
`"Normality of NaOH solution" =(1)/(2)N`
`"Normality of" H_(2)SO_(4) "solution"= (1)/(N)`
Volume of unused acid can be calculated by applying normality equation
`underset("Acid")(underbrace(N_(1)V_(1)))=underset("Base")(underbrace(N_(1)V_(1)))`
`1 xx V=(1)/(2) xx 60 = 30 cm^(3)`
Step II. Calculation of volume of acid used
`"Volume of acid added" = 50 cm^(3)`
`"Volume of unused acid" = 30 cm^(3)`
`"Volume of acid used"= (50-30) = 20 cm^(3)`
Step III. Calculation of percentage of nitrogen
Mass of compound = 0.50 g
`"Volume of acid used"=20 cm^(3)`
Normality of acid used = 1 N
`"Percentage of N" = (1.4 xx "Volume of acid used" xx "Normality of acid used")/("Mass of the compound")`
`=(1.4 xx 20 xx 1)/(0.50)=50%`