Question

Nitrogen gas and hydrogen gas react to produce ammonia according to the following equation.

N2+3H2→2NH3


The atomic mass of nitrogen is 14 g/mol
. The atomic mass of hydrogen is 1 g/mol
. When the reaction produces 68
grams of ammonia, how many grams of nitrogen were present initially?

(1 point)
Responses

12

12

112

112

56

56

4

4

Answer 1

Molar mass NH3 = 17 g/mol. 68 g NH3 = 68/17 = 4 mol NH3.
From N2 + 3H2 → 2NH3, 2 mol NH3 come from 1 mol N2, so 4 mol NH3 come from 2 mol N2 = 4 mol N atoms.
Mass of N = 4 mol × 14 g/mol = 56 g.

Answer: 56.