Potato and Sweet Potato Water Potential in Different Sugar Solutions

Variables:

Independent variable → They type of potato used

                                  → The molarity of the sugar solution

Dependent Variable → Weight change in the pieces of potato in the 20 hour period

Fixed Variables:

               -The volume of solution that is used in each test tube

               - The initial weight of the potato when placed in the test tube.

Materials:

• 1 Big potato 10 g                        
• 1 Big Sweet Potato 10 g                
• Cutting Blade                                                
• 1 Test Tube Rack                        
• Distilled Water
• 5 different types of sugar solutions 0.0M, .25M, .50M, .75M, 1.0M
• Weighing Scale
• Forceps
• 5,20 ml test tubes
• observation glass

Method:

• Label 5 test tubes with the molarity of the sugar solutions.
• Cut the potato pieces so that they are all of the same weight and fit into the test tubes with ease. 3g
• Place one piece into each of the 5 labeled test tubes
• Leave the test tubes in a room for 20 hours undisturbed
• Return after the 20 hour gap and remove the potatoes out of the test tube and place on the weighing scale and take their weight.
• Once finished repeat the same thing for the sweet potato.

Data and Findings

Weight Difference in Percentages:

• For potato:

1. 10%
2. 17.6%
3. -0.66%
4. -5.66%
5. -11.66%

• For sweet potato:

1. 17.3%
2. 15%
3. 4%
4. -7%
5. -10.66%

Graph 1 (Potato):

Graph 2 (Sweet Potato):

Conclusion:

What was found was that the concentration of the sugar solution increased while the weight of the potato decreased and this therefore, supports the hypothesis.

The reason for this occurrence is due to osmosis occurring between the vegetables and the sugar concentrations. Hence, potatoes gaining the most weight in distilled water whereas they would loose their weight in the highly concentrated sugar solutions.

The texture of the vegetables change as well due to process of osmosis over the 20 hour period due to the swelling up of cells which makes the potato firm. Whereas, when the sugar concentration is increased the water concentration in the solution along with the potato is decreased which leads to the potato forming a smoother softer texture.

Errors and Uncertainties:

• When one left the sugar solution out for 20 hours ants got into the sugar solution which could have affected the experiment.
• Timing could have been kept more accurate as no one was aware of when each potato was put into an individual test tube.
• Better manipulative skills.
• Checking the weighing scales properly as they could be inaccurate.