Osmosis Lab

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Osmosis Design Lab
November 19, 2011
Biology

Defining the Problem and Selecting the Variables

Research Question:
What will happen to mass of the cell when it is placed in different solutions while trying to reach equilibrium?

Background Information
Osmosis is the procedure where water or different types of liquids move through a semipermeable membrane. This type of passage is considered as simple diffusion where no energy is required. This means that the liquid will have to leave the cell or enter it so that equilibrium can be reached. Equilibrium is the state reached when the amount of concentration is equal between the cell and the solution it is placed in. When the concentration which is the solute has the same exact concentration of the cell which is the solvent the solution is known to be an isotonic solution. When the concentration of the solute is greater than the concentration of the solvent the solution is known to be a hypertonic solution. Finally, when the concentration of the solute is lower than the concentration of the solvent the solution is known to be a hypotonic solution. Therefore, hypertonic and hypotonic solutions aren’t at equilibrium.

Variables
* Independent
* The change in solution in milliliters
* Dependent
* The change in mass in grams
* Controlled
* Amount of solution in milliliter
* Same potato was used
* Initial mass of the potato slice in grams
* Temperature of the solution in Co
* Same amount of time where the potato stays in the solution in minutes

Hypothesis
“If the solution that the potato slice is placed in changes then the mass of the potato will increase or decrease. “

Qualitative and Quantitative Data
* Qualitative Data
* Change in the color of the potato
* Change in the shape of the potato
* Quantitative Data
* Change in the mass of the potato

Relating the Hypothesis to the Scientific Theory
When the mass of the potato slice increases, it means that it has been placed in a hypotonic solution. On the other hand, if the mass of the potato slice decreases, it means that it has been placed in a hypertonic solution.

Change in
Mass (grams)

Change in Concentration
This graph means that when the concentration increases, the mass increases, therefore they are directly proportional.

Controlling Variables
Materials
-5 test-tube that have milliliter indications-1 tablespoon -10 milliliters of water-1 scale
-10 milliliters of oil-1 sharp knife
- 10 milliliters of lemon juice-1 medium-sized potato
-10 milliliters of vinegar-Stirring rod
-10 milliliters of diluted iodine-Stopwatch
-Salt
Charts for Recording Data
Types of Solution| How was the Color and Shape of the Potato Affected| How was the Mass of the Potato Affected (uncertainty depending on the instrument used)| 10 milliliters of salt and water solution| 1.2.3.4.5.| 1.2.3.4.5.| 10 milliliters of oil| 1.2.3.4.5.| 1.2.3.4.5.|

10 milliliters of lemon juice| 1.2.3.4.5.| 1.2.3.4.5.|
10 milliliters of vinegar| 1.2.3.4.5.| 1.2.3.4.5.|
10 milliliters of diluted iodine | 1.2.3.4.5.| 1.2.3.4.5.| Explanation of Materials
Material| Picture| Explanation|
5 test-tube that have milliliter indications| | It is used to measure the exact amount of solution that has to be placed in the test-tube.| 1 tablespoon| | It is used to place the salt in the water and to remove the potato slice out of the solutions. | 1 scale| | It is used to measure the mass of the potato slice before and after it is placed in the solution. | 1 sharp knife| | It is used to cut the potato in slices. | 1 medium-sized potato| | It is used as the solvent.|

Salt| | It is used to make the water and salt solution.| Stirring rod| | It is used to stir the salt and water to make the water and salt solution.| Stopwatch | | It is used to measure how long the...
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