822Recognize that in a chemical reaction the mass of the reactants is equal to

the mass of the products (Law of Conservation of mass)

Recognize that in a chemical reaction the mass of the reactants is equal to the mass of the products (Law of Conservation of mass).

•Key concepts/skills: Level 1: Define key vocabulary.

• Level 2: Count the number of each • type of atoms on both sides • of a chemical equation to • determine whether • an equation is balanced or not.• Level 3: Balance a chemical equation using • coefficients.•

Recognize that in a chemical reaction the mass of the reactants is equal to the mass of the products (Law of Conservation of mass).

Key vocabularySubscriptYieldReactantProductCoefficientBalanceThe Law of Conservation of Matter

Recognize that in a chemical reaction the mass of the reactants is equal to the mass of the products (Law of Conservation of mass).

I. The Law of Conservation of Mass

A.Mass is neither created nor destroyed during a

normal chemical reaction.

B.That means that if you start a reaction with 10

atoms in the reactants, you have to finish the

reaction with 10 atoms in the product.

11 + 2 = 3 + 3

13 = 6???

Recognize that in a chemical reaction the mass of the reactants is equal to the mass of the products (Law of Conservation of mass).

C. The number of atoms has to be the same on both

sides of the arrow for each type of atom in the

chemical reaction.

D. Balancing equations is “balancing” the number

of atoms on both sides of the equation.

C 3 > C 1

H 8 > H 2

O 2 > O 3

Recognize that in a chemical reaction the mass of the reactants is equal to the mass of the products (Law of Conservation of mass).

E. Coefficient – numbers placed to the left of a symbol or formula telling how many molecules of a compound are in the equation.

H2O= 2 hydrogen and 1 oxygen3(H2O) = 6 hydrogen and 3 oxygen

4(CO2)

4NH3

3C6H12O6

Recognize that in a chemical reaction the mass of the reactants is equal to the mass of the products (Law of Conservation of mass).

I. Balancing equationsA. Steps

1. Count the number of each type of atom on both sides of the equation

2. Fix the element with the highest number of atoms first

3. Add coefficients to change the number of atoms

4. Never change the subscripts. H2O

C3H8 + O2 CO2 + H20

C 3 > C 1

H 8 > H 2

O 2 > O 3

45 3

Recognize that in a chemical reaction the mass of the reactants is equal to the mass of the products (Law of Conservation of mass).