Calculate the mass of water that is formed by the interaction of 28 g of potassium hydroxide with hydrochloric acid.

Let’s compose the equation for the reaction of interaction of potassium hydroxide with hydrochloric acid:
KOH + HCl = KCl + H2O;

Let’s find the molecular weight of potassium hydroxide:
39 + 16 + 1 = 56 g / mol;

Let’s find the amount of substance in potassium hydroxide:
28/56 = 0.5 mol;

The molecular weight of water is 18 g / mol.
There is the same coefficient in front of water as in front of potassium hydroxide. This means that the amount of substance in water is 0.5 mol. Let’s find the mass of water:
18 * 0.5 = 9 grams.

Answer: the mass of water is 9 grams.