Chemical Reactions

Science — Second Preparatory

Common mistakes

Comparison aspect	Main idea	Keywords
Mistake	thinking that every change in shape or colour is a chemical reaction. Correct: a chemical change happens when a new substance with a different composition is formed	thinkingeverychangeshape
Mistake	thinking that mass decreases in a reaction. Correct: mass is conserved so the total mass of the reactants equals the total mass of the products	thinkingmassdecreasesreaction
Mistake	thinking that a gas produced in a reaction has no mass. Correct: the gas has mass and it must be counted among the products	thinkingproducedreactionmass
Mistake	confusing breaking bonds with forming bonds. Correct: a reaction starts by breaking bonds in the reactants then new bonds form in the products	confusingbreakingbondsforming

Chemical Reactions · 6 / 7