osmosis required practical

• step 1: peel potato skin ; why do we peel potato skin?

  as it affects osmosis
• step 2: use a cork borer to make 3 cylinders of potato slices. why do we use a cork borer?

  to ensure the cylinders have an equal diameter
• step 4: use scalpel to trim cylinders to 3cm.
• step 5: measure length of cylinder using a ruler and measure the mass using a balance
• place each cylinder into a test tube:

  in the first test tube, add 10cm3 of 0.5 molar sugar solution.

  in the second test tube, add 10cm3 of 0.25 molar sugar solution.

  in the last test tube, add 10 cm3 of distilled water.
• why do we use distilled water and not normal tap water?

  there is no dissolved substances
• leave cylinders overnight to let osmosis occur.
• step 7: remove cylinders onto paper towel gently - do not press down. why do we remove cylinders onto paper towels and not press down?


  to remove surface water not the water within the cylinder.
• step 8; measure length of cylinder and mass of cylinder again. How do we know if osmosis has occurred?

  if the mass of the potato slices increases.
• what is the dependent variable?

  chip mass
• what is the independent variable?

  concentration of sugar solution
• how do we calculate percentage change?

  change in value/change in mass x100.