Name:_____________________________        Hr:___________        Date:___________

Lab: Gummy Bear Osmosis

Purpose:

Molecules are in constant motion and tend to move from areas of higher concentration to areas of lower concentration. Diffusion is defined as the movement of molecules from an area of high concentration to an area of low concentration. The diffusion of water molecules through a selectively permeable membrane is known as osmosis. Selectively permeable means that some molecules can move through the membrane while others cannot. Movement through the membranes is called transport. Diffusion and osmosis are passive forms of transport; this means that the process does not need energy to move from areas of high concentration to areas of lower concentration. Active transport requires energy to transport molecules from low concentrations to areas of high concentration.

Question:

How will soaking a Gummy Bear candy in distilled water affect the size of the bear?

Hypothesis:

This is a prediction, or your best guess, as to what will occur and why.

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Materials:

• 2 Gummy Bears
• Ruler
• Tape
• 2 Cups (3 oz Dixie cup, or something similar)
• Distilled water
• Salt
• Plastic wrap
• Electronic balance

Procedure:

1. Use the masking tape to label your cups with your names and class period.

1. Label one cup water and one cup salt water.

2. Use the ruler to find the height and width of your Gummy Bears. Be sure to use metric units (cm) and record the results of Gummy Bear 1 and Gummy Bear 2 in your data table.

1. Gummy Bear 1 will go in the water cup.
2. Gummy Bear 2 will go in the salt water cup.

3. Use a balance to find the mass of your Gummy Bears.

1. Use a piece of wax paper to protect the pan of the balance.
2. Remember to tear the scale after you add the wax paper, so that it does not contribute to the Gummy Bear’s weight.
3. Record the weight of Gummy Bear 1 (water) and Gummy Bear 2 (salt water) in your data table.

4. Record descriptive observations about the Gummy Bears. Record the observations in the data tables.
5. Fill both of your plastic cups ½ full with distilled water.
6. On the cup labeled salt, add 1 T (tablespoon) of salt.
7. Put Gummy Bear 1 into the cup labeled water.
8. Put Gummy Bear 2 into the cup labeled salt water. 
9. Set the cups aside for one day.
10. After the Gummy Bears have been in the water and salt water overnight, gently take them out of the water and salt water and pat them dry. Be very careful because the Gummy Bears are now extremely breakable.
11. Repeat steps 2 – 4 and fill out the data tables.

Data Tables

Bear #1 Distilled Water

Bear #2 Distilled Salt Water

Calculations:

Bear #1 in distilled salt water

Calculate the percent change in the size of the Gummy Bear:

% change in height =

(after soaking height – before soaking height / before soaking height) X 100 = __________%

(________ - _________ / ________) X 100 = ________%

% change in width =

(after soaking width – before soaking width / before soaking width) X 100 = __________%

(________ - _________ / ________) X 100 = ________%

% change in mass =

(after soaking mass – before soaking mass / before soaking mass) X 100 = __________%

(________ - _________ / ________) X 100 = ________%

 Bear #2 in distilled salt water

Calculate the percent change in the size of the Gummy Bear:

% change in height =

(after soaking height – before soaking height / before soaking height) X 100 = __________%

(________ - _________ / ________) X 100 = ________%

% change in width =

(after soaking width – before soaking width / before soaking width) X 100 = __________%

(________ - _________ / ________) X 100 = ________%

% change in mass =

(after soaking mass – before soaking mass / before soaking mass) X 100 = __________%

(________ - _________ / ________) X 100 = ________%

Graphing:

Graph the percent changes on a bar graph. Remember to include a title and label both axes.

Questions:

1. What happened to the Gummy Bear after soaking in distilled water overnight?

2. What happened to the Gummy Bear after soaking in salt water overnight?

3. Write a short paragraph to explain the results of this investigation using the concept of osmosis. Include specific data to support what you say.