My question concerns percent composition.

Question

Determine the percent composition of nitroglycerine, C3H5N3O9

Answer 1

The percent composition is given by the mass of each element divided by the total mass (x100%)

For C: 3 x 12.01 = 36.03 g

For H: 5 x 1.008 = 5.040 g

For N: 3 x 14.01 = 42.03 g

For O: 9 x 16.00 = 144.0 g

Total mass = 227.1 g

Percent composition:

% C = 36.03 g / 227.1 g (x100%) = 15.9%

% H = 5.040 g / 227.1 g (x100%) = 2.2%

% N = 42.03 g / 227.1 g (x100%) = 18.5%

% O = 144.0 g / 227.1 g (x100%) = 63.4%