Question

Mg + 2HCl --> H2 + MgCl2 How many moles of H2 will form from 20 moles of HCl

Answer 1

Hi!
Basically, you will want to cross product your 20 moles of HCl with the number of moles in your H2 (so 1), with that and the number of moles in the HCl (2), you will find that 10 moles of H2 will form from 20 moles of HCl