required practical: osmosis

• Osmosis

  The movement of water from a higher water potential to a lower water potential through a partially permeable membrane
• 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)
• Using a cork borer to cut the cylinders

  • Results in equal sized samples so changes in length and mass can be compared easily
• Blotting the cylinders with paper after removing them

  • Each cylinder may have a different amount of water on its surface, so masses may vary. Blotting cylinders allows masses to be comparable
• Handle cork borer and scalpel with care