Mr. Chapman
Matter, Change & Energy Review
Chemistry 20
Matter, Change & Energy Review
Attempt to complete this passage that represents some material you should already be familiar
with from Science 10. Every blank can be filled with one word, give it your best shot.
Chemistry is a natural science that deals with matter and the changes it undergoes.
Matter is anything that has mass and occupies space. Matter exists in three states,
solid, liquid, and gas.
Chemists use the scientific method to learn how matter can be changed and how
energy is involved in these changes. A physical combination of two or more substances
is called a mixture. A mixture has variable composition and may be identified as
homogeneous or heterogeneous. Homogeneous mixtures are known as solutions and
have uniform properties.
A pure substance is either a molecule or compound. Compounds are made up
elements, which are always present in the same ratio in a given compound.
Compounds can be separated into their constituent elements by chemical means only.
A change in the properties of a substance without a change in the composition is known
as a physical change. If the composition changes, then a chemical change has
occurred. In a chemical reaction, reactants are converted to products. Physical
changes are usually reversible, and many chemical changes are not easily reversible.
The Law of Conservation of Mass states that mass is neither created nor destroyed in
any physical or chemical reaction.
Mr. Chapman
Matter, Change & Energy Review
Chemistry 20
1. State whether each of the following is a homogeneous or heterogeneous
mixture:
Oxygen dissolved in water
HOMOGENEOUS
Carbon mixed with sand
HETEROGENEOUS
Apple Juice
HOMOGENEOUS
Vegetable Soup
HETEROGENEOUS
Sour milk
HETEROGENEOUS
2. When 400.0 grams of wood are burned, 30.0 grams of ash remain. What has
happened to the missing 370.0 grams of matter?
The matter was converted into a gas form and escaped.
3. Car batteries give off a potentially explosive mixture of gases. What type of
change is taking place in the battery? Justify your answer.
The reaction is chemical, since the original substance was not an explosive
gas but has become one. Explosiveness is a chemical property of matter, and
this is clearly not a property of the original batteries.