Question

the empirical formula of a compound is CH2 N2 and its molecular mass is 126.0. what is the molecular formula of the compound

Answer 1

Solution:

Step 1: Represent a molecular formula.

$\text{molecular formula} = (\text{CH}_{2}\text{N}_{2})_{n}$

Step 2: Calculate the empirical mass.

empirical mass = (12.0 g/mol × 1) + (1.0 g/mol × 2) + (14.0 g/mol × 2)

empirical mass = 42.0 g/mol

Step 3: Divide the molecular mass by the empirical mass.

$n = \frac{\text{molecular mass}}{\text{empirical mass}}$

$n = \frac{\text{126.0}}{\text{42.0}}$

$n = 3$

Step 4: Multiply the subscripts by the value of n to obtain the molecular formula.

$\text{molecular formula} = (\text{CH}_{2}\text{N}_{2})_{3}$

$\boxed{\text{molecular formula} = \text{C}_{3}\text{H}_{6}\text{N}_{6}}$

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