Question

Consider the balanced chemical equation shown below:

2 NH3 + 5 F2 ---> N2F4 + 6 HF

1. How many moles of N2F4 form per mole of reaction? (Answer is in mol / mol reaction)

2. If 0.022 moles of HF form, how many moles of reaction have been completed?

I tried both .5, and 0.0146 for answer for 1, and .0256 and then 0.0183 ​for my answer for 2 - but none of those are correct.

Answer 1

a) 2 moles of NH3 will form 1 mole of N2F4 and 5 moles of F2 will form 1 mole of N2F4

Hence F2 is the limiting reagent in the reaction, number of moles of F2 = 1. hence 5 moles of F2 will give one mole of N2F4

Hence moles of N2F4 form per mole of reaction = 1/5 = 0.2 moles

b) 5 moles of F2 will give rise to 6 moles of HF

Moles of F2 used = 0.022 * 5/6 = 0.0183333 moles

Moles of NH3 used = 0.0183333 * 2/5 = 0.00733333 moles

Moles of reaction completed = 0.01833333 + 0.0073333 moles = 0.02566666