(HT only) Calculate masses of reactants from a balanced symbol equation and a given mass of another substance.

In the subtopic Amounts of substances in equations (HT only), this learning objective focuses on (HT only) Calculate masses of reactants from a balanced symbol equation and a given mass of another substance. It sits within Use of amount of substance in relation to masses of pure substances for AQA GCSE Chemistry 8462 Unit 4.3, so the explanation must stay anchored to quantitative chemistry rather than drifting into a general chemistry idea. Approved keywords to use include HT only, balanced symbol equation. Balanced symbol equation. means an equation that shows the reactants and products of a chemical reaction with equal numbers of atoms for each element on both sides Avoid the mistake of students often confuse the mass of a substance with the number of moles when calculating the masses of reactants from a balanced symbol equation; instead, to fix this, remember to use the formula that relates mass, moles, and relative formula mass: mass = moles x Mr. Ensure you calculate the number of moles first before converting to mass For exam answers, always start by writing and balancing the chemical equation before performing any calculations