Osmosis

• What is the practical focus of the experiment described?

  The effect of different concentrations of solutions on plant tissue.
• What plant tissue is used in the osmosis experiment?

  Potato tissue.
• Why is it important to cut potato cylinders of the same diameter?

  To compare results more easily.
• How many potato cylinders are prepared for the experiment?

  Three potato cylinders.
• Why are the ends of the potato cylinders cut off?

  To remove the impermeable potato skin.
• What is the length of each potato cylinder measured for the experiment?

  Three centimeters.
• What equipment is used to measure the mass of the potato cylinders?

  A top pan balance.
• What is the mass of the potato cylinder before the experiment?

  1. 92 grams.
• What type of water is used in the first boiling tube?

  Distilled water.
• How much distilled water is added to the boiling tube?

  10 milliliters.
• Why is a bung added to the boiling tube?

  To prevent evaporation of the liquid.
• What concentration of sucrose is added to the second boiling tube?

  0.25 molar sucrose.
• What concentration of sucrose is added to the third boiling tube?

  0.5 molar sucrose.
• What happens to the potato cylinders after being left in the solutions overnight?

  The results are collected to observe changes.
• How is excess water removed from the potato cylinders after soaking?

  By rolling them on a paper towel.
• What is the length of the potato cylinder after being soaked in distilled water?

  32 millimeters.
• What is the mass of the potato cylinder after soaking in distilled water?

  1. 12 grams.
• What is the mass of the potato cylinder after soaking in the 0.25 molar sucrose solution?

  1. 06 grams.
• What happens to the potato cylinder in the 0.5 molar sucrose solution?

  It decreases in mass.
• What is the mass of the potato cylinder after soaking in the 0.5 molar sucrose solution?

  1. 62 grams.
• What calculation is performed to compare the results of the potato cylinders?

  Percentage change in mass.
• How is percentage change calculated?

  Change in mass divided by initial mass multiplied by 100.
• What does a positive percentage change indicate?

  An increase in mass.
• What does a negative percentage change indicate?

  A decrease in mass.
• What are the expected results of the osmosis experiment with varying sucrose concentrations?

  • In distilled water: Increase in mass and length of potato.
  • In 0.25 molar sucrose: Slight increase in mass.
  • In 0.5 molar sucrose: Decrease in mass.
• What is osmosis?

  • Movement of water across a semi-permeable membrane.
  • Water moves from an area of low solute concentration to high solute concentration.
• What does the graph of the experiment results typically show?

  • Gain in mass decreases as sucrose concentration increases.
  • A point where mass change may stabilize.
  • Loss of mass increases with higher sucrose concentration.