Question

What is the percentage composition of dimethylhydrazine?

Express your answers using three significant figures seperated by comas.

Answer 1

percent composition is the percentage mass of each element in the compound.

It is easiest to work it out using 1 mole of compound

molar mass C2H4N2 = 60.104 g

There are 2 mole C in each mole.
therefore mass C in 1 mole = 2 x 12.01 = 24.02 g

%C = mass C / total mass x 100/1
= 24.02 g / 60.104 g x 100 = 39.96 %

mass H in 1 mole = 8 x 1.008 g/mol = 8.064 g
%H = 8.064 g / 60.104 g x 100 = 13.42 %

mass N in 1 mole = 2 x 14.01 = 28.02 g
% N = 28.02 g / 60.104 g x 100 = 46.62 %

percent composition C2H8N2 is thus

39.96% C, 13.42 % H, 46.62 % N