DENSITY PREDICTIONS

1
LESSON 3

• DENSITY PREDICTIONS

2
OBJECTIVES

• MAKE PREDICTIONS, BASED ON THE FEEL OF AN OBJECT,
  ABOUT WHETHER AN OBJECT WILL FLOAT OR SINK
• USE DENSITY TO PREDICT WHETHER A SUBSTANCE WILL
  FLOAT OR SINK
• CALCULATE THE DENSITY OF TWO IMMISCIBLE LIQUIDS

3

• USE DENSITY TO PREDICT HOW DIFFERENT IMMISCIBLE
  LIQUIDS WILL BEHAVE WHEN MIXED WITH WATER IN A
  DENSITY COLUMN
• BUILD A DENSITY COLUMN
• USE DENSITY TO PREDICT HOW OBJECTS WILL BEHAVE
  WHEN PLACED IN A DENSITY COLUMN
• DISCUSS HOW KNOWLEDGE OF DENSITY CAN BE APPLIED

4

• COLLECT A TOTE TRAY OF MATERIALS CONTAINING
• 1 BLOCK OF TRANSPARENT PLASTIC
• 1 BLOCK OF WHITE PLASTIC
• 1 BLOCK OF ALUMINUM
• 1 BLOCK OF WAX
• 1 125-mL bottle containing 50 mL of vegetable oil
• 1 125 mL bottle containing 50 mL of corn syrup
  (list contd on next slide)

5

• 2 100-mL graduated cylinders
• 1 250-mL beaker containing colored water
• 1 copper cylinder
• 1 nylon spacer
• 1 test tube brush
• 1 electronic balance

6
PREDICT

• IN YOUR GROUPS, PREDICT WHICH BLOCKS WILL SINK OR
  FLOAT. RECORD YOUR PREDICTIONS IN YOUR DATA
  TABLE.
• TEST YOUR PREDICTIONS USING THE LARGE TUB OF
  WATER AT YOUR TABLE.

7

• IS THERE A RELATIONSHIP BETWEEN DENSITY AND
  FLOATING AND SINKING IN WATER? IF SO, DESCRIBE
  WHAT THIS RELATIONSHIP IS.
• Answer yes, If a substance has a density
  greater than 1 (water) then it will sink. If
  its density is less than 1 (water) then it will
  float.

8
INQUIRY 3.1 - BUILDING A DENSITY COLUMN

• LOOK AT TABLE 2 ON YOUR STUDENT SHEET 3.
• HOW COULD YOU DETERMINE THE DENSITY OF THE OIL?
• Answer Think about how we measured the density
  of water in lesson 2. Use the following
  procedure to complete Data Table 2 - Calculating
  Density.

9

• A. ACCURATELY MEASURE THE MASS OF THE EMPTY
  CYLINDER (Remember that although cylinders may
  look the same, they may not have the same mass).
• ACCURATELY MEASURE THE MASS OF THE CYLINDER AND
  LIQUID.
• CALCULATE THE MASS OF THE LIQUID.
• MEASURE THE VOLUME OF THE LIQUID.
• CALCULATE THE DENSITY USING THE MASS/VOLUME
  FORMULA.

10

• DETERMINE THE DENSITY OF THE TWO LIQUIDS
  FOLLOWING THE DIRECTIONS IN YOUR STUDENT GUIDE.
• IMPORTANT USE A DIFFERENT GRADUATED CYLINDER TO
  DETERMINE THE MASS AND VOLUME OF EACH LIQUID.
• PUT YOUR DATA IN TABLE 2 ON STUDENT SHEET 3.1.

11
PREDICT

• WHAT WILL HAPPEN WHEN YOU MIX THE THREE LIQUIDS?
  
• RECORD AND EXPLAIN YOUR PREDICTIONS AS WELL AS
  DRAW YOUR PREDICTION ON THE PREDICTION CYLINDER
  ON Student Sheet 3.1.

12
TEST

• MIX THE THREE LIQUIDS IN ONE CYLINDER FOLLOWING
  THE DIRECTIONS IN YOUR STUDENT GUIDE.
• FILL IN THE OBSERVATION CYLINDER (LABELING THE
  LIQUIDS AND GIVING THEIR DENSITIES) ON STUDENT
  SHEET 3.1.

13

• ADD THE OBJECTS IN THIS ORDER
• 1. COPPER CYLINDER
• 2. NYLON SPACER
• RECORD WHAT HAPPENS BY DRAWING THE OBJECTS IN THE
  OBSERVATION CYLINDER, LABEL THEM, AND WRITE THE
  OBJECTS DENSITIES.

14
CLEAN UP

• POUR THE LIQUIDS FROM THE CYLINDER INTO THE LARGE
  TUBS AT THE FRONT AND BACK OF THE ROOM.
• ONE PERSON FROM EACH GROUP NEEDS TO WASH OUT THE
  CYLINDERS AND BEAKERS (AS NEEDED).
• DRY OUT THE LABWARE AND TOTE TRAYS.

15
REFLECTIONS 3.1

• DO THE LIQUIDS MIX TOGETHER (MISCIBLE) OR FORM
  DISTINCT LAYERS (IMMISCIBLE)?
• Answer distinct layers
• WHAT IS THE RELATIONSHIP BETWEEN THE DENSITY OF A
  LIQUID AND ITS POSITION IN THE GRADUATED
  CYLINDER?
• Answer The less dense liquid (water) went to
  the top and the most dense (corn syrup) went to
  the bottom.

16
GLOSSARY

• IMMISCIBLE- LIQUIDS THAT ARE INSOLUBLE IN ONE
  ANOTHER (THEY SEPARATE)
• MISCIBLE - LIQUIDS THAT ARE ABLE TO MIX WITH
  ANOTHER