Coachbook Chapter 1 Lesson 5: Law of Conservation of Matter

Chemical Equation

A chemical equation is a representation of a chemical equation that uses chemical symbols and formulas.

Reactants: the substances that are present before the reaction takes place
Products: the substances that are present after the reaction takes place
Coefficient: the number before a chemical formula (multiply by the subscript)
Subscript: a small-sized number on the bottom right of the symbol. It refers to the number of atoms of the element

The Law of Conservation of Matter

During a chemical reaction, atoms do not change from one element to another. They merely rearrange into different molecules. The number of atoms of each element remains the same. This is true for EVERY chemical reaction.
"Matter cannot be created or destroyed"

Multiple Choice

According to the Law of Conservation of Matter, which of the following is true in a chemical reaction?

• total mass of the reactants is greater than the total mass of the products

• the total mass of the reactants is equal to the total mass of the products

• Elements change into other elements, but new matter is not created

• matter cannot change form, but new matter can be created

Multiple Choice

Look at the incomplete equation below.

Ca+Cl₂ $$\rightarrow$$ ?

The reactants are shown. How many Chlorine (Cl) must be present in the product that forms from this reaction?

• 1

• 2

• 3

• 4

Multiple Choice

During a chemical reaction, methane (CH₄) and oxygen (O₂) combine to produce carbon dioxide (CO₂) and water (H₂O). The balanced chemical equation identifies the reactants and products for this reaction, along with some of their masses.

CH₄+2O₂ $$\rightarrow$$ CO₂+2H₂O

16g + ? = 44g + 36g

• 16g

• 36g

• 44g

• 64