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Page 146
Mixtures and Compounds
How do you know a new compound has
formed?
SKILL FOCUS
Inferring (8.3.b)
PROCEDURE
1
Place a piece of chalk into each beaker. Break the chalk if necessary so it can
rest flat at the bottom of the beaker.
2 Using the masking tape, label one beaker water and the other beaker
vinegar.
3 Pour water over the chalk in the beaker marked water. Pour vinegar over the
chalk in the beaker marked vinegar. Be certain the chalk is completely covered
in each beaker.
MATERIALS
•
•
•
•
•
2 pieces of chalk
2 beakers
water
vinegar
masking tape
TIME
30 minutes
4 Record what happens to the chalk in each beaker.
5 Allow the liquids in both beakers to evaporate. Record your observations
of the materials left behind.
WHAT DO YOU THINK?
• Which beaker contained only a mixture? Which
beaker now contains a new compound?
• What might be an indication that a compound
was formed?
CHALLENGE Try mixing other substances with
vinegar. Can you predict which substances will
behave like the chalk?
RESOURCE CENTER
CLASSZONE.COM
Find out more about
mixtures.
Comparing Mixtures and Compounds
Although mixtures and compounds may seem similar, they are
very different. Consider how mixtures and compounds compare
with each other.
The substances in mixtures remain the same substances.
Compounds are new substances formed by atoms that
bond together.
• Mixtures can be separated by physical means. Compounds can
be separated only by breaking the bonds between atoms.
• The proportions of different substances in a mixture can vary
throughout the mixture or from mixture to mixture. The proportions of different substances in a compound are fixed because
the type and number of atoms that make up a basic unit of the
compound are always the same.
•
Check Your Reading
146 Unit 2: The Structure of Matter
How is a mixture different from a compound?
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