What is the empirical formula for a compound containing 38.8 g carbon, 16.2 g hydrogen and 45.1 g nitrogen?

2 Answers
May 26, 2018

H2NCH3 or NCH5

Explanation:

To find the empirical formula change the mass to moles Then find a ratio between the moles.

For Carbon 38.812=3.233 moles

For Hydrogen 16.21=16.2 moles

For Nitrogen 45.114=3.22 moles.

The ratio for Carbon and Nitrogen is 1:1

3.2333.22=1.00

The ratio of Hydrogen to both Carbon and Nitrogen is 5:1

16.23.22=5.03

So the ratio is 1 C to 1 N to 5 H.

H2NCH3

Nitrogen usually forms three bonds one to Carbon and 2 to Hydrogen atoms. Carbon usually forms four bonds one to Nitrogen and 3 to Hydrogen atoms.

May 26, 2018

The empirical formula is CH5N.

This may be methylamine, CH3NH2, derived from ammonia, NH3, in which one H atom is replaced by a methyl group -CH3. However, we can't know this for certain unless we are given the molecular mass.

Explanation:

The empirical formula of a compound represents the simplest whole number ratio of elements in the compound.

We must first determine the moles of each element in the compound by dividing the given mass by the molar mass.

Since the masses of all of the elements equal 100.1 g, we can use the masses as given.

mol C: 38.8g C12.011gmol=3.23 mol

mol H: 16.2g H1.008gmol=16.1 mol

mol N: 45.1g N14.007gmol=3.22 mol

To determine the subscripts of the empirical formula, we find the lowest whole number ratio for each element by dividing the moles of each element by the least number of moles, in this case 3.22 mol.

C: 3.233.22=1.00

H: 16.13.22=5.00

N: 3.223.22=1.00

The empirical formula is CH5N.

Note: If the mol ratios are not all whole numbers, you will need to multiply each mole ratio by the same factor that will make all mol ratios whole numbers.

This may be methylamine, CH3NH2, derived from ammonia, NH3, in which one H atom is replaced by a methyl group -CH3. However, we can't know this for certain unless we are given the molecular mass.

![https://en.wikipedia.org/wiki/Methylamine](useruploads.socratic.org)