NAME: _________________________________________________________ DATE: _________________ CLASS PERIOD: _________
LAB: Air Freshener Osmosis! (33 Total Points)
Background information: Remember that the cells in your body are always striving to maintain homeostasis – a
sort of internal stability as external conditions change. All organisms go through this (in fact, it is one of the
characteristics of living things!). The most common example from your body is your ability to keep your internal
body temperature at 98.6°F. The diagram to the right
shows how your body responds to dehydration:
What are some other examples of maintaining
homeostasis inside your body? (2 points)
Today’s lab is designed to review the following SOL
topics:
1) Scientific Investigation and Experimental Design
2) Cellular Transport
I. PRE-LAB QUESTIONS:
Water always moves from an area of high water concentration to an area of low water concentration. If
concentrations of water is the same, it will move in both directions. Underneath the diagrams of the cells below,
write whether water: moves out of the cell, moves into the cell, or moves both in and out of the cell (1 point each):
45% H2O
55% solute
25% H20
75% solute
10% H2O
90% solute
10% H20
90% solute
42% H2O
58% solute
67% H20
33% solute
3. In today’s lab, you will be examining how air freshener beads respond to being placed in water with different
salinity levels (salinity refers to the concentration of salt in the water): fresh water, low salinity water, and high
salinity water. We will use them to represent what might happen to cells if we placed them in the different
solutions. At the end of the experiment, you will calculate the change in weight (in grams) for each set of beads in
the different solutions. To help you write your hypothesis, predict what will happen to the beads in each of the
three conditions (hint: use what you wrote in the boxes in the first pre-lab question!) (1 point each)
Air freshener beads in Fresh water:
NAME: _________________________________________________________ DATE: _________________ CLASS PERIOD: _________
Air freshener beads in Low Salinity water:
Air freshener beads in High Salinity water:
4. Fill in the blanks in this sentence to identify the variables in your experiment (2 points):
5. What should be some constants in your experiment (1 point)?
6. What is the control in your experiment (1 point)?
II. MATERIALS:
3 cups
Beaker
30 air freshener beads
Fresh water
Low Salinity water
High Salinity water
Digital scale
Sharpie marker
Plastic spoon and paper towel
III. PROCEDURE:
1. Use a marker to label your three cups: F, LS, and HS. (F = fresh, LS = low salinity, and HS = high salinity.)
2. Pour 50 ml of fresh water into the cup labeled F, 50 ml of Low Salinity water into the cup labeled LS, and 50
ml of High Salinity water into the cup labeled HS. Set the cups aside.
3. Carefully place a beaker on the digital scale and push the “Zero” button (this sets the scale to zero).
4. Add 10 air freshener beads to the beaker, wait for the scale to settle, and record the weight under “Initial
Weight” beneath the heading “Fresh Water.” Place the 10 air freshener beads in the cup labeled “F”.
5. Repeat step 4 twice, once for the Low Salinity treatment, and once for the High Salinity treatment. Record
both weights under “Initial Weight” beneath the headings “Low Salinity” and then “High Salinity.” Place the
beads in their proper cups (LS and HS).
6. Let the air freshener beads sit in the cups for at least 30-45 minutes.
7. Use your plastic spoon to scoop the beads very carefully from the cup labeled “F” and place them gently on
the paper towel. Wait 10 seconds for them to dry.
8. Place a beaker on the digital scale and push the “Zero” button.
9. Using your plastic spoon, carefully scoop the beads into the beaker, wait for the scale to settle, and record
the weight under “Final Weight” beneath the heading “Fresh water.”
10. Repeat steps 7 – 9 twice, once for the Low Salinity treatment and once for the High Salinity treatment.
Record both weights under “Final Weight” beneath the headings “Low Salinity” and “High Salinity.”
11. Calculate the change in weight for each treatment.
12. Answer the post-lab questions.
DATA
Initial weight
(grams) – 1 point
Final weight
(grams) – 1 point
Change in weight
(grams) – 1 point
FRESH WATER
LOW SALINITY WATER
HIGH SALINITY WATER
NAME: _________________________________________________________ DATE: _________________ CLASS PERIOD: _________
AIR FRESHENER OSMOSIS LAB: POST-LAB QUESTIONS
1. Draw a diagram below to show your results. Use circles for the cells, and draw arrows to represent the way that
water moved. (3 points)
2. Did your results support or fail to support your hypothesis? Why do you think this happened? (3 points)
3. What are some possible sources of error in this experiment? How could you improve it if you were to do it
again? (3 points)
4. In what ways are the air freshener beads (and what happened to them) similar to the cells in your body? (3
points)