Easy chem question that i dont understand. help plz

1.) Calcium hydride, CaH2, reacts with water to form hydrogen gas.?

CaH2(s) + 2 H2O(l) Ca(OH)2(aq) + 2 H2(g)

Question: How many grams of CaH2 are needed to generate 54.0 L of H2 gas if the pressure of H2 is 815 torr at 22 Celcius?

n= PV :RT
n=1,07 atm x 54L : 0,082 x 295 K
n=2,38 mol H2

mol CaH2=mol H2 : 2
=1,19 mol
grams of CaH2 =1,19 x 42
=50,2 g