What mass of CaH2 is produced at the end of 5g of Ca with excess H2?

Question

What mass of CaH2 is produced at the end
of 5g of Ca with excess H2?

Answer 1

CaH2 --> Ca + H2↑
1) n(Ca) = 5g : 40g/mol = 0,125mol
2) n(CaH2) = n(Ca) = 0,125mol
3) m(CaH2) = 0,125mol * 42g/mol = 5,25g