Sodium metal and water react to form hydrogen and sodium hydroxide. if 17.94 g of sodium react with water to form 0.78 g of hydrogen and 31.20 g of sodium hydroxide, what mass of water was involved in the reaction

The mass of water involved in reaction is calculated as follows

in a reaction mass of reactants should = mass of products

mass of product = mass of hydrogen + mass of sodium hydroxide

= 0.78 g + 31.20 g = 31.98 grams

mass of reactant = mass of sodium metal + mass of water

let the mass of water be represented by y

=17.94g + y = 31.98 g

like terms together

y=31.98 g - 17.94 g = 14.04 grams of water