Chemistry homework

Question

When 21.44 moles of silicon reacts with 17.62 moles of nitrogen, how many moles excess are left over?

Answer 1

First, write a correctly balanced equation:

3Si + 2N₂ ==> Si₃N₄

Since the mole ratio of Si to N₂ is 3:2 we can determine which reactant is limiting:

21.44 moles Si/3 = 7.15

17.62 moles N2/2 = 8.81

Si is limiting

Now, using 21.44 moles of Si, we can find the moles of N₂ left over:

21.44 moles Si x 2 moles N₂/3 mol Si = 14.29 moles N₂ used up

moles N₂ left over = 17.62 moles - 14.29 moles = 3.33 moles N₂ left over.