How many moles of silicon react?

Question

i have the reaction of 18.0g of silicon: 3Si + 2N2 Si3N4.

how many moles of silicon react?
how many moles of nitrogen molecules must react?

and what is product form? i dont know what it means.

Answer 1

Silicon nitride is formed from 3 mols Si and 4 mols N.

18.0 g Silicon is 0.643 mols Silicon because it weighs 28.01 grams per mol.

For every 3 mols Silicon, 4 mols Nitrogen must react, therefore,
0.482 mols Nitrogen must react (this is expressed as N, not N2)

To express that nitrogen as N2, it would be 2 mols N2 instead of 4 mols N. So 0.241 mols N2.