The Law of Conservation of Matter

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https://www.youtube.com/watch?v=3lHHOiTdmK4

We’ve talked about changes in matter… The evaporation of a puddle of water Rust forming on a metal fence PHYSICAL CHEMICAL

HOWEVER… No matter is created or destroyed by such changes! The total amount of matter remains constant.

The Law of Conservation of Matter During a chemical reaction, matter cannot be created or destroyed. Even though the matter may change from one form to another, the same number of atoms exists before and after the change takes place!

Since the overall mass of the matter does not change… The mass of the reactants – the substances there before the reaction occurs – must equal the mass of the product – the substances there after the reaction takes place. Mass of Reactants Mass of Products

NUMBERS IN EQUATIONS

The Formation of Rust Iron Rust Hard, gray-colored metal Flaky, orange-red solid

When iron reacts with oxygen in the air, they form rust or IRON OXIDE. This is written as: Iron + Oxygen Iron Oxide

TAKE A LOOK AT THE NUMBERS Each made of TWO oxygen atoms Fe Fe O2 Fe2O3 Fe2O3 Fe Fe O2 O2 2Fe 3O 2Fe 3O 4 Fe 6 O REACTANTS Totals 4 Fe 6 O PRODUCTS

All Chemical Reactions follow the Law of Conservation of Matter With Iron Oxide, the MASS STAYS THE SAME! The total number of iron atoms and oxygen atoms in the reactants is the same as that in the product. The atoms were just rearranged! No new atoms were created and none were destroyed!

Determining the Mass of Reactants and Products REMEMBER: The mass of the reactants is always equal to the mass of the products. Mass of Reactants Mass of Products

Example: Tin Fluoride Tin + hydrogen fluoride -> tin fluoride + hydrogen What’s the total mass of the reactants? 158.72 g So what should the mass of the products be? 118.7 g 40.02 g

Total Mass of Reactants: 158.72 g Tin + hydrogen fluoride -> tin fluoride + hydrogen If we know the mass of the tin fluoride, can we figure out how much hydrogen was produced? Subtract the mass of one product from the total mass. 156.71 g 2.01 g Total Mass of Reactants: 158.72 g

Please complete the LCM worksheet Please take the next 5 minutes to read the background information. This will go on pg. 52 in IAN You then need to answer the 4 experiments and answer the short answer. Please answer the short answer under your worksheet on pg. 52. Whatever is not completed in class will be homework. This will be a graded assignment.