The answer is Make sure you are working with a properly balanced chemical equation. Convert grams of the substance given in the problem to moles. Construct two ratios - one from the problem and one from the chemical equation and set them equal. ... Convert moles of the substance just solved for into grams. Step 1: Convert known reactant mass to moles. ... Step 2: Use the mole ratio to find moles of other reactant. ... Step 3: Convert moles of other reactant to mass. Balance the equation. Convert units of a given substance to moles. Using the mole ratio, calculate the moles of substance yielded by the reaction. Convert moles of wanted substance to desired units.