An excess of Ca(s) is added to 180g of distilled water at STP. What volume of H2 gas can be produced?
a) 448 L
b) 224 L
c) 112 L
d) 22.4 L
...................Ca + 2H2O ==> Ca(OH)2 + H2
moles H2O = grams/molr mass = 180/18 = 10
Convert mols H2O to mols H2 this way:
1moles H2 gas = 0 mols H2O x (1 mol H2/2 mols H2O) = 10 x 1/2 = 5
You know 1 mol of gas occupies 22.4 L @ STP; therefore, volume H2 = 5 moles H2 x (22.4 L/mol) = ?