Calcium hydride reacts with water to form calcium hydroxide and hydrogen gas...?

CaH₂ + 2H₂0 --------> Ca(0H)₂ + 2H₂

Calculate the moles of Hydrogen

n = m/mr

8.5/2

= 4.25mol of hydrogen needed

Compare their ratios

CaH₂ : H₂

1 : 2

x : 4.25

x = 2.125mol of CaH₂ needed

Find the molar mass of CaH₂

Ca - 1 x 40 = 40

H - 2x 1 = 2

mr = 42g/mol

Now finally find the mass

m = n x mr

= 2.125 x 42

= 89.25g

Balanced chemical equation - 2CaH2 + H2O - 2CaOH + H2

To find the number of moles in hydrogen gas go sample/molar mass of substance

=4.22moles

4.22*2 since ratio of H2 to 2CaH2 is 2 =8.44

Molar mass of calcium hydride is 42.096

To get grams

8.44*42.096=3555.29grams

CaH2 + 2H2O = Ca(OH)2 + 2H2

nH2 = 8.5 g/ 2 g/mol = 4.25 mol

nCaH2 = 1/2nH2 = 1/2 x 4.25 mol = 2.125 mol

mCaH2 = 2.125 mol x 42g/mol = 89.25 g