Question
Chemistry Question on Mole concept and Molar Masses
Compound A contains 8.7% Hydrogen, 74% Carbon and 17.3% Nitrogen. The molecular formula of the compound is,
Given : Atomic masses of C, H and N are 12, 1 and 14 amu, respectively.
The molar mass of the compound A is 162g mol–1.
A
C4H6N2
B
C2H3N
C
C5H7N
D
C10H14N2
Answer
C10H14N2
Explanation
Solution
The correct answer is (D) : C10H14N2
| Element | %mass | Moles | Whole number ratio |
|---|---|---|---|
| C | 74 | 6.17 | 5 |
| H | 8.7 | 8.7 | 7 |
| N | 17.3 | 1.236 | 1 |
Empirical Formula = C5H7N
Empirical formula mass = 81 g
n × 81 = 162
n = 2
Hence, molecular formula is C10H14N2.