Now, in the first step, before we find the moles, we first have to find the amount in grams of water. To find the amount of grams of water, we must first look up the density of water. The density of water is 1 gram per ML. So we take our volume of 100 MLS multiplied by 1 gram per ML the MLS can't sell and we get 100 grams of water in our beaker. Now, in the second step, we have to find the molecular weight of water. To find a molecular weight of water, we simply add up the atomic weights.