Osmosis Required Practical Flashcards
What is osmosis?
Osmosis is the movement of water molecules from an area of high water concentration (or low solute concentration) to an area of low water concentration (or high solute concentration) through a semi-permeable membrane. It is a type of passive transport that does not require energy.
What are the key factors that affect the rate of osmosis?
The rate of osmosis can be affected by:
Concentration gradient: The greater the difference in solute concentration between two solutions, the faster osmosis will occur.
Temperature: Higher temperatures increase the rate of osmosis, as the water molecules move faster.
Surface area: A larger surface area of the membrane or cells allows for more osmosis to occur.
Time: The longer the duration of the experiment, the greater the effects of osmosis.
What is a semi-permeable membrane, and why is it important in osmosis?
A semi-permeable membrane allows only certain molecules (typically water) to pass through while blocking others, like larger solute molecules. It is essential in osmosis because it enables the movement of water while preventing the movement of larger solute molecules, facilitating the process of water diffusion from one area to another
In an osmosis investigation with potato chips, what would you expect to happen if you place a potato chip in pure water? Why?
The potato chip would increase in mass as water moves into the cells by osmosis. This happens because the water outside the potato cells has a higher water potential (lower solute concentration) than the water inside the cells, so water enters the cells.
How would you set up an experiment to investigate the effect of different concentrations of salt (NaCl) solution on the rate of osmosis in potato cells?
Step 1: Cut potato chips to equal size and shape.
Step 2: Prepare salt solutions with different concentrations (e.g., 0%, 5%, 10%, 15% NaCl).
Step 3: Place each potato chip into a separate beaker containing a different concentration of salt solution.
Step 4: Leave the chips in the solutions for a set amount of time (e.g., 30 minutes).
Step 5: After the time has passed, remove the chips, blot them dry, and measure their mass.
Control variables: Temperature, type of potato, size of potato chips, time in solution, volume of solution.
Dependent variable: Change in mass of the potato chips.
What is a control variable in an osmosis experiment, and why is it important to control variables like temperature, time, and type of potato?
A control variable is any factor that is kept constant during the experiment to ensure that the results are valid and that only the independent variable (e.g., salt concentration) is affecting the outcome. Controlling variables like temperature, time, and potato type ensures that these factors do not influence the results, making the experiment fair.
In an osmosis experiment, if the mass of a potato chip decreases after being placed in a salt solution, what does this suggest about the concentration of the salt solution?
If the mass of the potato chip decreases, it suggests that the salt solution has a higher concentration than the water inside the cells. Water moves out of the cells into the solution by osmosis, causing the chip to lose mass.
If the potato chip’s mass increases in a sugar solution, what does this suggest about the solution and the process occurring inside the cells?
If the potato chip’s mass increases, it suggests that the solution has a lower concentration of solutes (such as sugar) compared to the water inside the potato cells. Water moves into the cells from the solution, causing the cells to gain water and increase in mass.
How could you improve the accuracy of an osmosis experiment?
To improve accuracy:
Ensure all potato chips are cut to the same size and shape.
Use a precise balance to measure the mass of the chips.
Keep temperature constant, as temperature affects the rate of osmosis.
Use the same type of potato to ensure consistency in results.
Ensure solutions are mixed thoroughly to achieve even concentrations.
What are some limitations of using potato chips for investigating osmosis, and how could you address these limitations?
Some limitations include:
Variation in potato tissue: Different potatoes may have different water content or cell structure.
Surface area: The surface area of the chips may not be uniform, affecting the rate of osmosis.
Solution absorption: The potato may not absorb the solution evenly.
Solutions: Standardize the size of the chips, cut them consistently, and ensure uniform conditions.
If you were to repeat the experiment with a higher concentration of sugar solutions, what do you predict would happen to the rate of osmosis and the changes in mass of the potato chips?
If you use a higher concentration of sugar solution, the potato chips are likely to lose more mass because the higher concentration of sugar would draw more water out of the potato cells. The osmotic gradient would be greater, leading to more water leaving the cells
