Page 1: Law of Conservation of Mass and Law of Definite Proportions
Law of Conservation of Mass
The Law of Conservation of Mass, discovered by Lavoisier, states that the total mass of reactants equals the total mass of products in a chemical reaction. This fundamental principle is crucial for balancing chemical equations and understanding stoichiometry.
Example: In a reaction where 10g of X and 10g of Y produce 3g of Z and T, the mass of T must be 17g to conserve the total mass of 20g.
Highlight: In a closed system, the total mass remains constant before and after a chemical reaction.
Law of Definite Proportions
Also known as Proust's Law, this principle states that a chemical compound always contains the same elements in the same proportions by mass, regardless of its source or method of preparation.
Example: In water (H₂O), the mass ratio of hydrogen to oxygen is always 1:8, or 11.1% hydrogen and 88.9% oxygen by mass.
Vocabulary: Stoichiometry - The quantitative relationship between reactants and products in chemical reactions.
The page includes several practice problems applying these laws, helping students calculate mass ratios, determine chemical formulas, and predict product masses based on reactant quantities.