Osmosis in Potato Tissue
Aim: To see the effect of different concentrations of salt solutions on
potato.
Hypothesis: In hypotonic solutions, osmosis will move water into
the potato, whilst in hypertonic solutions, osmosis will move water
out of the potato.
Apparatus: Potato, distilled water, 1%, 5% and 10% salt (NaCl)
solutions, cork borer, tile, knife, boiling tubes, balance, measuring
cylinder, filter paper
Risk Assessment:
Risk
Cuts from cork borer, broken
glass or knife
Slips from spills
Safe Practice
Care using sharp objects
Clean up any spilt liquids
immediately
Variables:
1. Control variables - keep the volume of solution and time the same
for each experiment
2. Independent variable – _______________________________
3. Dependent variable -- ________________________________
Method:
1. Use the cork borer to cut 3 cylinders of potato, taking care with
fingers.
2. Trim the potato cylinders to the same length.
3. Measure the length and mass of each cylinder and test its
firmness by gently bending it.
4. Label boiling tubes: water, 1% salt, 5% salt, 10% salt and place
20 ml of the correct solution into each tube.
5. Place a potato cylinder in each solution, leave for 30 minutes.
6. Blot potato dry, then reweigh and measure length and firmness.
Results: Table to show effect of different concentrations of solutions
on potato cylinders
Before Experiment
Solution
Firmness
Length
(cm)
Mass (g)
Distilled
water
1% salt
5% salt
10% salt
Observations
Record any observations here
After experiment
Firmness
Length
(cm)
Mass (g)
Calculations:
% change in length = (change in length / starting length) X 100
% change in mass = (change in mass / starting mass) X 100
Solution
change in % change in
length (cm)
length
change in
mass (g)
% change in
mass
Distilled
water
1% salt
5% salt
10% salt
Discussion:
Write a discussion which describes the results and any
patterns/trends observed. Note any anomalies.
Conclusion:
Write a brief conclusion restating the aim and then outline if the
results supported the hypothesis.