Question

If you start with 70 grams of nitrogen and 20 grams of hydrogen and combine them, how many grams of ammonia will you get and how many grams of hydrogen are leftover? pls don't use moles but atoms. thanks

Answer 1

N2(g) + 3H2(g) ------> 2NH3

stoichiometrically 2atoms of N reacting with 6 atoms of H

70grams of Nitrogen contain 70 × 6.022×10^23 /14.007= 3.0095×10^24atoms

20grams of Hydrogen contain 20 ×6.022×10^23/1.007=1.1960×10^25atoms

So, No of atom of Hydrogen reacted = (6/2)×3.0095×10^24=9.0285×10^24

No of Hydrogen atom left = 11.960×10^24 - 9.0285×10^24= 2.9315×10^24atoms

mass of Hydrogen left = (1.007g/6.022×10^23)×2.9315×10^24=4.902g

Nitrogen is limiting

2 Nitrogen atom give 2NH3 molecule

3.0095×10^24atoms of N give 3.0095×10^24 atoms of NH3

Mass of NH3 produced = (17.028g/6.022×10^23)×3.0095×10^24=85.098g