The equation for the reaction of hydrogen and oxygen is:
[tex]2H_2 + O_2 \rightarrow 2H_2O[/tex]
[tex]M_r(H_2) = 2\\\\\therefore n(H_2) = \frac{1}{2}= 0.5mol = n(H_2O)\\\\m(H_2O) = 0.5 \times M(H_2O) = 0.5 \times 18 = 9g[/tex]
Thus, the theoretical yield of water is 9 grams.
