A compound is found to be 15.65% H and 31.07% N, with the remainder from carbon, by mass.Determine the empirical formula of the compound.

Question

Quizplus · Accepted Answer

Assume we have 100 g of this compound, which means we have 15.65 g of hydrogen and 31.07 g of nitrogen. The mass of carbon can be calculated by subtracting the mass of hydrogen and nitrogen from 100 g:

Mass of carbon = 100 g - 15.65 g - 31.07 g = 53.28 g

Next, we need to convert the masses of each element to moles:

moles of H = 15.65 g / 1.008 g/mol = 15.53
moles of N = 31.07 g / 14.007 g/mol = 2.219
moles of C = 53.28 g / 12.011 g/mol = 4.437

Divide each of the mole values by the smallest one to get an empirical formula:

H: 15.53 / 2.219 = 7
N: 2.219 / 2.219 = 1
C: 4.437 / 2.219 = 2

So the empirical formula is NC2H7, which matches option B.

A Compound Is Found to Be 15