Question

how many grams of calcium hydride are needed to form 4.550g of hydrogen gas

Answer 1

Molar mass:

CaH2 = 42.094 g/mol

H2 = 2.01 g/mol

CaH2 + 2 H2O = Ca(OH)2 + 2 H2

42.094 g ------------------------------ 2 x 2.01 g
?? ( mass of CaH2) --------------- 4.550 g

4.550 x 42.094 / 2 x 2.01 =

191.5277 / 4.02 => 47.64 g of CaH2

hope this helps!