PURE SUBSTANCE OR MIXTURE

1
LESSON 11

• PURE SUBSTANCE OR MIXTURE?

2
OBJECTIVES

• Determine a meaning for the term pure
  substance.
• Distinguish between pure substances and mixtures.
• Discover techniques for determining whether
  several samples of matter are pure substances or
  mixtures.

3
GETTING STARTED

• Look at Student sheet 11.1. Answer steps 1-3.
• Lets look at some of your definitions of pure
  substance. Lets record these on the board.
• What are some of your examples of pure
  substances? Lets record these on the board

4
HOW CAN YOU TELL THE DIFFERENCE?

• How can you tell whether something is pure or a
  mixture?
• Lets brainstorm some answers.

5

• Construct a concept map using the question How
  an you tell whether something is a pure substance
  or a mixture? as the central theme.

How can you tell whether something is a
pure substance or a mixture?
6
SAFETY TIPS

• WEAR SAFETY GOGGLES AT ALL TIMES DURING THE
  INQUIRY.
• DO NOT TASTE ANY OF THE SUBSTANCES

7
INQUIRY 11.1

• DETERMINING WHETHER SUBSTANCES ARE PURE OR
  MIXTURES

8
PROCEDURE

• Collect the materials and check its contents for
  the following
• 8 substances labeled A-H
• 4 magnifying loupes
• 2 lab scoops
• 2 dropping pipettes
• 4 petri dish lids
• 4 sheets of white paper
• 4 sheets of black paper
• 1 magnet
• 4 test tubes
• 1 test tube rack

9

• You will investigate samples A through H as fully
  as possible using the apparatus in their trays.
• Determine whether it is a pure substance or a
  mixture.
• Record your answers AND reasons in Table 1 of
  your student sheet.
• HINT Use the black and white paper as
  background for the petri dishes.
• Youll be given 20 minutes to complete this part
  of the inquiry. You may want to split up the
  work among members of your group.

10
CLEAN UP

• Dispose of mixtures G and H in the waste
  container.
• Wash the test tubes and return the materials to
  the tray.
• Wash your hands at the end of the inquiry.

11
REFLECTIONS 11.1

• Answer the following on your student sheet.
• 5. How can the properties of pure substances be
  used to discover whether a sample is a mixture?
• 6. Were the samples well mixed? How did the
  extent of mixing affect your investigation?
• 7. If you are not satisfied with your original
  definition of a pure substance, write a new one
  in the space provided.