N h2o = mh20/Mh20
= 8.0g/18g/mol
=0.44 mol
therefore n O = 0.44mol
therefore n H2 = 0.88 mol
m H2 = n H2 * M H2
= 0.88 mol * 2 g/mol
=1.76 g
If the equation is not balanced, you have extra of one substance. If you try to do an experiment, you could wind up with a totally different outcome. Its kind of like baking a cake. If the ingredients aren't the right amounts, you dont get an edible cake.
Chemicals dissolved in water. Calcite is a good example, if I'm not mistaken.
