Osmosis of Potato in Glucose Solutions

A. Research Question

What problem/relationship are you going to investigate?

How does the concentration of glucose solution affect the mass of potato sticks?

(independent variable) (dependent variable)

Here's a short introductory video.

If the concentration of glucose outside the potato sticks increases then the mass of the potato sticks will decrease because water will move into an area with a higher concentration of solute.

1.potatoes

2.water

3.glucose

4.scale

5.plate to hold potatoes

6.beaker

7.measring cup

8.potato cutter

9.pencil and notebook (for recording data)

1. Cut 15 pieces of potato into the same size or be within 4.4 - 6.5 grams

2. pour in a concentration of 1.00M of glucose (20ml Glucose) in
a plate

3.pour in a concentration of 0.75M of glucose and the rest with water (15ml glucose) in a plate

4.pour in a concentration of 0.50M of glucose and the rest with water (10ml glucose) in a plate

5.pour in a concentration of 0.25M of glucose and the rest with water (5ml glucose) in a plate

6.pour in a concentration of 0.00M of glucose and the rest with water (0ml glucose) in a plate

7.mesure the mass of the potato before placing it into the solution

8.place three potatoes into each concentration

9.label each plate with the concentration and the mass of each potato before placement.

10.come back after 24hours and measure each potato's mass

Interpreting & Explaining the Data:

As seen in
the graph, we can clearly see that as the glucose concentration decreases the percentage of decrease in the potato’s mass also decreases and eventually becomes an increase. This is the reason why I used the percentage in mass change as my y-axis and why I used the concentration of glucose solution as my x-axis, it is because it allows you to see if the percentage of mass change is affected by the concentration of glucose solution and water. The reason I used POCM is because it is much more accurate than the mass change of the potato, this is more accurate because not all the potatoes have the same mass as others. Samples with different mass their mass change can be different under the same experimental condition, but the POCM could be much accurate. This supports my hypothesis which states that “If the concentration of glucose outside the potato sticks increases then the mass of the potato sticks will decrease because water will move into an area with a higher concentration of solute.“ this is shown in the graph and the table. This can also be shown in the isotonic area of the graph. Between the concentration of 0.4 and 0.6, we can see there is a point where the mass change gets to zero, this is because the concentration of water inside the potato is isotonic to the glucose solution. My data validated to be reliable because I did not only attempt one trial per group instead I did three which increases the accuracy of my data results.

As seen in the table data the less concentration of glucose solution we add the less the decrease in mass and the more increase in mass we have. This is not only shown in the data table but also, it is shown in the graph which shows a steady decrease to an increase in mass, all of this supports and validates my hypothesis which states “If the concentration of glucose outside the potato, sticks increase then the mass of the potato sticks will decrease because water will move into an area with a higher concentration of solute.” This is validated by my graph and my experiment results. This is because water moves to an area with a higher concentration of solute. Which is , in this case, glucose solution. The more glucose there is the more amounts of water that will leave the potato which also means a decrease in mass as the glucose increases outside of the potato.

The method I experimented with did allow me to understand and test the idea I had, which is my research question. The procedure uses a total of 20 ml and different concentrations while keeping the total at 20 ml this allows my result to be accurate. The procedure asks to cut out 15 potato sticks and make them as similar as possible, this also allows my results to be accurate. Also, it measures the mass change in percentage (POCM) which can be more accurate than measuring the change in gram. All of this helps me to answer my research question as accurately as possible.

Limitations of the Procedure:

There are always possible sources of error. One of many that I found was the different masses of potato sticks. This can affect the mass change in grams which also makes it less accurate. There could have been some errors with measuring the correct amounts of solute, this could affect the accuracy of my result.

the picture is an example from https://www.youtube.com/watch?v=jTDATlaBV-o.. used due tp lack of materials, I was not able to get any of the materials needed due to lockdown

The procedure can be improved by keeping a constant temperature. This affects the experiment in multiple ways one of many is the concentration being different because of it being evaporated, since the temperature changes through out the day the concentration may change because of water being evaporated. This can be avoided by placing the petri dish in an environment with a constant temperature such as a fridge or a cooler. Another possible improvement is making sure that the potato is fully submerged into the solution throughout the experiment. This can be done my increase the total amount of liquids in the petri dish from 20ml to 30ml.

Going Further:

We can extend this investigation by using different solutions. Instead of using water which keeps glucose as a molecule, if we use salt water this can affect the state of glucose from a molecule to possibly turning into negative and positive ions. We can also change the dependent variable from measuring the mass of the potato to measuring the concentration of liquids, and seeing if there is more glucose solution left or more water left and why.

When you're at home, having all the materials needed may be hard this is why I came up with a simpler way of extracting the potatoes at home. As you can see in the pictures below, I have used an old pen to pull out the potato sticks by puncturing the potato with the stick and then taking it out of the pen. As you can see the result is a very similar result to having all the materials of a lab. (The reason I couldn't use lab materials was because of lockdown and not being able to leave the house for materials related to this.)

Asghari, Yas. “The Effect of Osmosis on Potatoes in Different

Concentrations of Sucrose Solutions | Natural Science | International Baccelaurate.” Athenology, Natural Science | International Baccelaurate | Athenology, 4 Apr. 2018, www.athenology.com/single-post/2017/09/23/The-effect-of-osmosis-on-potatoes-in-different-concentrations-of-sucrose-solutions.

Lobo, Tricia. “Science Experiments on the Osmosis of a Potato.” Sciencing, 2 Mar. 2019, sciencing.com/science-experiments-osmosis-potato-8360195.html.

Sauce, Science, director. Osmosis in Potato Strips - Bio Lab. YouTube, YouTube, 11 June 2017, www.youtube.com/watch?v=jTDATlaBV-o.