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Practical: Observing Osmosis in Gummy bears
BACKGROUND INFORMATION
BACKGROUND INFORMATION
Molecules are in constant motion, and tend to move from areas of higher concentrations to lesser concentrations. 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.
Osmosis is the movement (transport) of water (small dots) through a selectively permeable membrane from an area of high concentration to an area of low concentration.
Diffusion and osmosis are passive forms of transport; this means that do not need energy to move areas of high concentration to areas of low concentration.
Gummy Bears are popular candies made of gelatin, starch, and sugar.
Activity
AIM
To observe the effects of osmosis on gummy bears when placed in distilled and salt water solutions.
HYPOTHESIS
Make a prediction based on what you have learned thus far as to what will happen to the size of the gummy bear in each of the two different solutions.
MATERIALS (per group)
3 x gummy bears
2 x 50 mL glass beakers
masking tape
distilled water
salt
teaspoon
fork
electronic scales
METHOD
Find the mass all three gummy bears and find the average mass of a single gummy bear. Record in logbook under results heading.
Average mass of gummy bear (g) = Total weight / 3
Using masking tape, label the two beakers, salt and distilled water.
Place one teaspoon of salt into the beaker labelled salt.
Add approximately 25 mL of distilled water to each beaker and gently stir the one with salt.
Add a single gummy bear to each beaker and leave overnight.
The next day, qualitatively observe your gummy bears and record your descriptions in the results section.
Gently pour out the water and carefully catch your gummy bear using a plastic fork.
Find the mass of each gummy bear and record your results
RESULTS
Use the following table to record your gummy bear weights.
DISCUSSION
Draw a diagram of your gummy bear to show the net movement of water for both conditions, distilled and salt water. Identify which solution is hypotonic and which is hypertonic.
In a paragraph use words to explain what occurred. Make sure to include terms such as diffusion, osmosis, hypotonic, hypertonic, movement, solute and solvent.
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