Law of Conservation of Mass

Law of Conservation of Mass

The law of conservation of matter says that mass cannot be created or destroyed.

Law of Conservation of Mass

In a reaction, matter cannot be created or destroyed. That means that the mass of all reactants in a reaction will be equal to the mass of all the products.
The mass can change form in the reaction, but the matter is neither created, or destroyed.

Law of Conservation of Mass

All chemical reactions can demonstrate the law of conservation of matter.

Chemical Equations

2H₂ + O₂ → 2H₂O

​Write the below equation in your notebook.

Chemical Equations

2H₂ + O₂ → 2H₂O

​Reactants

​Products

​yields

​Label your equation.

Chemical Equations

​Reactants

Products

​before
on the left
goes into reaction

after
on the right
produced by reaction

​Create a T-Chart to compare and contrast reactants and products.

Multiple Choice

In the equation shown, what are the reactant(s)?

• N₂ + H₂

• NH₃

Multiple Choice

In the equation shown, what are the product(s)?

• N₂ + H₂

• NH₃

Chemical Equations

2H₂O → 2H₂ + O₂

​Copy this equation into your notebook.

Chemical Equations

2H₂O → 2H₂ + O₂

​coefficient

subscript

​coefficient

subscripts

​Label your equation.

Chemical Equations

2H₂O → 2H₂ + O₂

To balance a chemical equation, you can change (or add) coefficients in an equation.

Multiple Choice

To balance an equation you should:

• ONLY change subscripts.

• ONLY change coefficients.

• Change BOTH subscripts and coefficients.

Multiple Choice

What does the number 4 represent in 4NH₃?

• Subscript

• Superscript

• Coefficient

Multiple Choice

What does the number ₃ represent in 4NH₃?

• Subscript

• Superscript

• Coefficient

​Review:

Next you will review counting atoms and bonding. You may use your notes if you want.

Multiple Choice

How many sodium atoms are in NaHCO_3​?

• 1

• 2

• 3

Multiple Choice

In an ionic bond, a nonmetal bond with a

• metal

• nonmetal

Multiple Choice

The picture shows Hydrogen and Carbon atoms bonding together by sharing electrons. Which type of bond is shown?

• Ionic

• Covalent

Match

Match the number of atoms of each element in C₆H₈O_7​​.

• C

• H

• O

6

8

7

• 6

• 8

• 7

Multiple Choice

CaCl

• Ionic Bond

• Covalent Bond

Multiple Choice

The picture shows Lithium and Fluorine atoms bonding together by transferring an electron. Which type of bond is shown?

• Ionic

• Covalent

Multiple Choice

NH₃

• Ionic Bond

• Covalent Bond

Multiple Choice

How many aluminum atoms are in Al₂O₃?

• 3

• 2

• 5

Multiple Choice

NaO

• Ionic Bond

• Covalent Bond