Calcium oxide reacts with water

Your reaction will produce 0.624 g of hydrogen gas.

Start by writing the balanced chemical equation for this reaction

#Ca_((s)) + 2H_2O_((l)) -> Ca(OH)_text(2(s]) + H_text(2(g]) uarr#

Notice that you have a #1:1#mole ratio between calcium and hydrogen gas. This tells you that, regardless of how many moles of calcium react, you produce an equal number of moles of hydrogen gas.

Determine how many moles of calcium reacted by using its molar mass

#12.4cancel("g") * "1 mole Ca"/(40.078cancel("g")) = "0.3094 moles Ca"#

#0.3094cancel("moles Ca") * ("1 mole "H_2)/(1cancel("mole Ca")) = "0.3094 moles "##H_2#