Question

Which expression represents the percent by mass of nitrogen in NH4NO3?

Answer 1

Answer:

This question is incomplete. The completed question is below

Which expression represents the percent by mass of nitrogen in NH4NO3?

A) 14 g N/80 g NH₄ NO₃ ₓ 100%

B) 28 g N/80 g NH₄ NO₃ ₓ 100%

C) 80 g NH₄ NO₃ /14 g N ₓ 100%

D) 80 g NH₄ NO₃ /28 g N ₓ 100%

The correct option is B

Explanation:

To calculate the percentage by mass of nitrogen in the compound, the formula will be

total mass of nitrogen/total mass of compound    × 100

Atomic mass of nitrogen (N) is 14 g/mol

There are 2 nitrogen atoms present in the compound as highlighted below

Total mass of nitrogen (N) present in NH₄ NO₃ = 14 × 2 = 28g

Atomic mass of hydrogen (H) is 1 g/mol. There are 4 hydrogen atoms present in the compound, NH₄NO₃.

Atomic mass of oxygen (O) is 16 g/mol. There are 3 oxygen atoms present in the compound, NH₄NO₃

Total mass of the compound =

(14 × 2) + (1 ×4) + (16 × 3) = 80g

Hence, the percentage by mass of nitrogen in the compound (as shown in the formula earlier) is

28g of N/80g of NH₄NO₃ × 100%

Answer 2

W(N)={2M(N)/M(NH₄NO₃)}*100%

w(N)={2*14.0 g/mol/80.0 g/mol}*100% = 35%