How many grams of hydrogen, H2, would be required to produce 40.0 grams of ammonia, NH3?

Question

Balance the following reaction, then answer the question below.

H₂(g) + N₂(g) =   NH₃(g)

How many grams of hydrogen, H₂, would be required to produce 40.0 grams of ammonia, NH₃?

Answer 1

Hey Alexa,

1) Balance your equation. I'd start by balancing Nitrogen first, then adjusting as necessary. This is important, as you will eventually need to know the ratio between moles of H₂ and moles of NH₃

2) Determine the # of moles of NH_3. Do this by calculating the molar mass, which you can always check online. Molar mass is measured in g/mol, so if you divide 40.0 g by the molar mass, this will tell you how many moles of NH₃ you have.

3) Use the molar ratio (found from the balanced equation) to set up a conversion factor: # moles NH₃ * (coefficient for H₂ / coefficient for NH₃

4) Convert moles of H₂ into grams_. Find the molar mass of H₂, then reverse step #2: convert from moles into grams to get your final answer.

As a check, your answer must be less than 40.0g, due to conservation of mass in a chemical reaction.

Hope this helps,

Chris