Osmosis

• What is osmosis?


  Osmosis is the movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.
• Why is osmosis considered a special case of diffusion?

  Because it specifically involves the movement of water molecules across a membrane.
• What is a partially permeable membrane?

  A partially permeable membrane is one with very small holes that allow only tiny molecules, like water, to pass through.
• What happens to water molecules during osmosis?

  Water molecules pass both ways through the membrane, but there is a net flow into the region with fewer water molecules.
• What is the effect of osmosis on a strong sugar solution?

  The strong sugar solution becomes more dilute as water moves into it from the region of higher water concentration.
• What is the process of osmosis in terms of concentration gradients?

  • Water moves from an area of higher water concentration to an area of lower water concentration.
  • This movement continues until equilibrium is reached.
• What is the first step in the osmosis experiment using potato cylinders?

  Cut up a potato into identical cylinders and prepare beakers with different sugar solutions.
• What should one of the sugar solutions be in the osmosis experiment?

  One should be pure water and another should be a very concentrated sugar solution (e.g., 1 mol/dm²).
• How do you measure the effect of osmosis on potato cylinders?

  Measure the mass of the cylinders before and after leaving them in the solutions for twenty-four hours.
• What does an increase in mass of the potato cylinders indicate?

  It indicates that the cylinders have drawn in water by osmosis.
• What is the dependent variable in the osmosis experiment?

  The dependent variable is the chip mass.
• What must be kept constant to ensure a fair test in the osmosis experiment?

  All other variables such as volume of solution, temperature, time, and type of sugar used must be kept the same.
• What errors might occur during the osmosis experiment?

  Errors may occur if potato cylinders are not fully dried or if water evaporates from the beakers.
• How can you reduce the effect of errors in the osmosis experiment?

  By repeating the experiment and calculating a mean percentage change at each concentration.
• How can you determine the rate of osmosis in the potato cylinders?

  • Leave the potato cylinders for 30 minutes.
  • Calculate the change in mass (in grams) and divide by the time taken (in minutes).
  • The units for the rate would be g/min.
• What is the unit for the rate of osmosis calculated in the experiment?

  The unit for the rate is g/min.