Question

Diazomethane has the following composition by mass: 28.57% C, 4.80% H, and 66.64% N. The molar mass of diazomethane is 42.04 g/mol. Find the molecular formula of diazomethane.

Answer 1

CH2N2

Step-by-step explanation:

To find the molecular formula, we must first find the empirical formula as follows:

28.57% C - 28.57g of Carbon

4.80% H - 4.80g of Hydrogen

66.64% N - 66.64g of Nitrogen

Next, we convert this mass values to mole by dividing by their respective atomic mass.

C = 28.57/12 = 2.38mol

H = 4.80/1 = 4.80mol

N = 66.64/14 = 4.76mol

Next, we divide each mole value by the smallest mole value (2.38mol)

C = 2.38mol ÷ 2.38 = 1

H = 4.80mol ÷ 2.38 = 2.01

N = 4.76mol ÷ 2.38 = 2

The empirical ratio of C, H and N is therefore 1:2:2. Hence, the empirical formula is CH2N2

To calculate the molecular formula;

(CH2N2)n = 42.04 g/mol

{12 + 1(2) + 14(2)}n = 42.04

{12 + 2 + 28}n = 42.04

{42}n = 42.04

n = 42.04/42

n = 1.00009

Since n = 1, molecular formula is CH2N2