Law of Conservation of Mass

causes a chemical change, which creates a new substance with new and different properties.

is the result of a chemical reaction.

When a chemical reaction occurs, atoms rearrange and combine into new substances that have different properties.

In a chemical reaction matter is not lost or created but combines in a new and different way. The total number of atoms does not change so therefore the total mass remains the same.

A chemical equation is a shortened written expression of a chemical reaction.

Chemical equations consist of three basic parts 1.Reactants- the starting substances, located on the left side of the arrow. 2.An arrow- yield sign. 3.Products- the ending substances, located on the right side of the arrow.

Symbols and formulas represent the elements and compounds of the reactants and products. A chemical equation helps scientists easily communicate which substances react together to form new products or materials. Numbers are placed in front of the chemical formula to indicate the number of molecules of the compound or element involved in the reaction. These numbers are called coefficients. ****Subscripts can never be changed, however coefficients can.

The law of conservation of mass states that matter cannot be created or destroyed. The number of atoms of each element found in the reactants and the number of atoms of each element found in the products must be equal. When the number of atoms on the reactant side is equal to the number of atoms on the product side the chemical equation is balanced and follows the Law of Conservation of Mass.

1 box of cake mix+3 eggs+2 cups of water  24 cupcakes How many eggs do I need if I have 2 boxes of cake mix? How many cups of water do I need for 2 boxes of cake mix? How many cupcakes will I get with 2 boxes of cake mix? How many cupcakes will I get if I have 2 boxes of cake mix, 6 eggs and 2 cups of water?

1. C + O 2  CO 2 ReactantsProducts C= O= C= O= 11 22

2. 6C + 6H 2 O  C 6 H 12 O 6 ReactantsProducts C= O= C= O= H=

3. Na + Cl  NaCl ReactantsProducts Na= Cl= Na= Cl= 11 11

4. CH 4 + O 2  CO 2 + 2H 2 O ReactantsProducts C= O= C= O= H=

What can we do??? 4. CH 4 + O 2  CO 2 + 2H 2 O

5. CO 2 + H 2 O  H 2 CO 3 ReactantsProducts C= O= C= O= H=

6. 2HCl + CaCO 3  CaCl 2 + CO 2 + H 2 O ReactantsProducts C= O= C= O= H= Ca= Cl= H= Ca= Cl=