Question

0.2033g of an organic compound in Dumas method gave 31.7 mL of moist $N_2$ at ${14}^o$C and 758 mm pressure. Percentage of 2 N in the compound is (Aq. Tension at ${14}^{o}C=14mm$):

• A. $18.16$ %
• B. $17.89$ %
• C. $15.60$ %
• D. $16.00$ %

Answer 1

The correct option is A $18.16$ %

Dumas method
$V_1=31.7mL$
$P_1$=atmospheric pressure-tension +760-14=746mm
$T_1{14}^{\circ }C={287}^{\circ }K$
Volume of $N_2$ at STP=$\frac{P_1{V}_1\times 273}{760\times 287}=\frac{746\times 31.7\times 273}{760\times 287}$
$\therefore volumeof{N}_{2}atSTP=29.598ml$
% $N_2=\frac{MallMassof{N}_2}{22400mL}\times \frac{valumeatSTP\times 100}{Massofcompound}=\frac{28}{22400}\times \frac{29.6\times 100}{6.2033}$
$N_2=18.19\%$