Conservation of Mass

What is it? Conservation of Mass is a principle that states that when a chemical reaction occurs matter is not created or destroyed. This means that the total mass of the reactants MUST equal the total mass of the products.

Open vs. Closed system Open system- where matter can enter the system or escape to the surroundings Example: a burning match Closed system- where the entire reaction is contained; nothing can enter or leave the system Example: Pear decay (pg. 197 in book)

Balancing Equations Due to Conservation of Mass we must balance all equations to make sure that we have an equal number of reactants and products of the same element to achieve the same mass on both sides. H2O MgO

Classifying Chemical Reactions There are three major classifications of reactions Synthesis Decomposition Replacement

Synthesis This is when 2 or more things are combined to make a more complex substance Water is an example of a synthesis reaction

Decomposition This is like it sounds where a more complex compound is broken down into its smaller parts Hydrogen peroxide into water and O2 gas

Replacement Whenever one element takes the place of another in a compound; they switch places Cu2O to Cu + CO2