RP 3 - Osmosis

• What is osmosis?


  The movement of water from a higher water potential to a lower water potential through a partially permeable membrane
• What are the steps to carry out an investigation into osmosis using potato tissue?

  1. Cut identical potato cylinders using a cork borer
  2. Measure and record the length and mass of cylinders using ruler and balance
  3. Add each cylinder to one of three solutions: 1M sugar solution, 0.5M sugar solution, and distilled water
  4. Leave cylinders in tubes overnight
  5. Remove cylinders from tubes and blot them using paper towels
  6. Record length and mass of each cylinder
  7. Draw graph of change in mass in grams (y axis) against concentration of solution in mol dm^-3 (x axis)
• Why is it necessary to use a cork borer to cut the potato cylinders?

  It results in equal sized samples so changes in length and mass can be compared easily
• Why is it necessary to blot the potato cylinders with paper after removing them from the solution?

  Each cylinder may have a different amount of water on its surface, so blotting allows masses to be comparable
• What safety precautions should be taken during the osmosis experiment?

  Handle cork borer and scalpel with care