Biology Coursework: Osmosis Investigation - page 3
Keywords: biology coursework osmosis potato potatoes sucrose molar mass change
By ruth on 08/11/2006 17:19:48
Level: GCSE Key Stage 4 (Years 10-11)
Page Number: 3 of 7 pages: 1 2 3 4 5 6 7
up the following solutions:
Boiling tube 1 Boiling tube 2 Boiling tube 3 Boiling tube 4 Boiling tube 5 Boiling tube 6
Solution/m 0.0 0.2 0.4 0.6 0.8 1.0
Method:
Firstly I took six boiling tubes and placed them in a test tube rack. I added labels to them stating the concentration. Then I made up the solutions. Each added up to 30 cm and I used the following concentrations of sucrose solution 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 molar. I measured the correct proportions of water and solution using the measuring cylinders and then added these to the boiling tubes. I then cut 18 pieces of potato out using the cork borer and scalpel. Then on my white tile I split these into 6 groups of three pieces of potato. I weighed each bit and for 2 of the three pieces I added differently coloured pins. This is so when I re-weigh them I can identify which are which. I recorded in a table the weight of each piece of potato. I then added the three pieces of potato in to the boiling tubes. Finally I covered the boiling tubes with cling film to stop evaporation. I left the potato in the solution for 90 minutes. I then weighed each piece of potato again after blotting it to remove excess water and recorded the difference in mass.
Safety:
Risk Precaution Action
Using scalpels Could cut finger Be very careful and don’t put fingers too near the blade.
Glass boiling tubes falling over and breaking Boiling tubes easily roll over and could fall off a desk and smash which could easily cut someone Never leave lying unattended on a table, put in a test tube rack.
Accident with sucrose solution Could spill sucrose Wear overall and glasses
Solutions:
The solutions were made up as follows:
Concentration of sucrose solution/m Volume of water/cm3 Volume of 1m sucrose solution/cm3
0.0 30 0
0.2 6 24
0.4 12 18
0.6 18 12
0.8 24 6
1.0 0 30
Diagram:
Apparatus:
Piece of apparatus Specification Reason
Boiling tubes For experiment to take place in
Test-tube rack - To hold the boiling tubes
6 white labels - To identify which concentration was in each boiling tube
Beaker of water 100cm3 For the solutions
Beaker of sucrose solution 100cm3 For the solutions
pipettes - To transfer water/sucrose into measuring cylinders
Piece of apparatus Specification Reason
One potato - To observe the rate of osmosis in different concentrations of sucrose solution
Cork borer - To get pieces of potato to be cut up for the experiment
Scalpel - To
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