Question

How do you calculate the composition of a reactant by knowing the mass of the products after combustion? (In words)

Answer 1

From the law of consevation of energy, it is states that;

the total mass of the reactants equals the total mass of the products leading to the insight that the relations among quantities of reactants and products typically form a ratio of positive integers. This means that, how much quantity of the product formed is depends on the number of moles of initial reactant were participated in the reaction.

From the product formation we can find how many moles of reactants were conjumed in the reaction.