Download CLASSROOM CONNECTORS

CLASSROOM CONNECTORS
TIME REQUIRED:
one hour
MATERIALS:
Salt, piece of zinc, hydrochloric acid, Mg ribbon, nail, bottle of coke, candle,
matches, heat source
SIGNIFICANT TERMS:
Chemical change, chemical property, property, physical change, physical property
SET:
Matter is generally described by giving its physical and chemical properties.
Today we will discuss what these properties are and learn some common
examples.
INSTRUCTION:
A property is a set of identifying characteristics about a substance. Physical
properties are easy to identify because they involve your senses of sight, touch,
taste, smell and hear. Common examples of physical properties include the color,
size and texture of an object. The characteristics, however, are not enough to
identify a material. Additional ones such as density, and freezing point are
needed.
Any slight change in these physical properties brings about physical changes such
as when ice melts. The substance changes size, shape or state, but does not change
into a new substance with new properties. One of the most common examples of a
physical change is the melting of ice. Ice is solid H20; when it melts, it becomes
liquid H20.
Chemical properties are those properties a substance possesses because of its
action or lack of action with other substances. Reaction with an acid, or reaction
with oxygen (combustion) are just a couple of examples of chemical properties.
Studying chemical properties is usually done when chemical changes are
observed. A chemical change is a change in which one or more new substances
with new properties is formed. When paper is burned, the ashes formed are
entirely different from the original paper that was burned.
Chemical and physical properties and changes are characteristic of every
substance. See if you can identify the following as physical or chemical by
creating a chart and marking each example under the proper category:
1. tearing a piece of paper (Physical)
2. burning wood (Chemical)
3. a candle 5 inches long (Physical)
4. boiling water (Physical)
5. adding hydrochloric acid to zinc (Chemical)
ACTIVITIES:
(In order to do some of the following, you may have to get chemicals from the
high school chemistry department.)
1. Dissolve a small amount of salt in water. Is this a chemical change or a physical
change? (Physical) Allow the solution to evaporate. Is this a chemical or physical
change? (physical)
2. Add a small piece of zinc to 5 ml of hydrochloric acid. Is the reaction a
chemical or physical change? (Chemical)
3. Burn a small piece of Mg ribbon by holding it with tongs in a flame until it
catches fire. Do not observe directly. Is the change a chemical or physical one?
(Chemical)
4. Put a small nail into a bottle of Coke and leave it for one week. Is the change a
chemical or physical one? (Chemical)
5. Light a candle and allow it to burn five minutes. Extinguish. Is the change in
the candle physical or chemical? (Physical)
CLOSURE:
We have discussed chemical and physical properties and changes. Turn to your
neighbor and describe one physical and one chemical property of a substance.
Then have your neighbor explain to you the difference between a physical and
chemical change.
GLOSSARY
chemical change - a change in which a new substance with new properties is
formed
chemical property - a property that describes how a substance interacts or fails to
interact with another
physical change - a change in size, shape, or state that does not result in the
formation of a new substance
physical property - a property that relates to an object's size, shape, or state. These
are determined by the senses.
property - a set of characteristics that may help to identify the substance