Hypotonic - Hypertonic Solutions

Purpose:  The purpose of this lab investigation is to demonstrate how water moves by osmosis from a hypotonic solution through a semipermeable membrane into a hypertonic one.  A hypotonic solution has fewer solutes per unit volume when compared to a solution on the opposite side of a semipermeable membrane.  The solution on the opposite side has more solutes per unit volume and is hypertonic.  For example a 2% sugar solution is hypotonic to a 10% sugar solution when the two are separated by a semipermeable membrane.  The 10% solution is hypertonic. 

Materials and methods:  For this lab investigation, the student will need two potato slices, a finger bowl of tap water, and a finger bowl of salt water.  Drop a potato slice into the tap water finger bowl and the other slice into the salt water finger bowl.  Allow the potato slices to stand in the bowls for a minimum of 30 minutes.

Your set up should resemble the model below:

Experiment:  After 30 minutes, feel each of the potato slices.

Conclusion:  What did each slice feel like and why?

What is the semipermeable membrane in this experiment?

In the finger bowl of tap water, the water is hypotonic but what is hypertonic here?

In the finger bowl of salt water, the salt water is ________________ to the potato.

In both of these experiments, water moves from the _______ tonic solution into the ________tonic one.

Label the diagrams above using the words hypotonic and hypertonic on each drawing.

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