Biology Coursework: Osmosis Investigation - page 4
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: 4 of 7 pages: 1 2 3 4 5 6 7
cut the potato after a longer piece has been cut using the cork borer
Coloured pins - To enable me to recognise which piece of potato is which before recording the final weight
Weighing scales - To calculate the weight of each piece of potato
Kitchen roll - To blot the potato before the weight after the experiment, to remove excess water
forceps - To retrieve the potato after the experiment has finished
Tile - To cut the potato on
Cling film - To cover the boiling tubes so that there is no evaporation which could affect the results
Measuring cylinder 50cm3 To measure the sucrose/water
Measuring cylinder 10cm3 To measure the sucrose/water
Stop clock - To time the 90 minute experiment
I have planned to produce reliable evidence by doing three repeats. This will try and help me to identify anomalous results and produce an accurate average.
Results:
Concentration of Sucrose Solution/m Colour of Pin Weight Before/g Weight After/g Change in Weight/g Percentage Change of Weight/% * Average Percentage Change of Weight/%
0.0 Orange 0.78 1.00 +0.22 28.0
22.9
None 0.92 1.10 +0.18 19.6
Red 1.11 1.34 +0.23 21.0
0.2
Orange 1.10 1.18 +0.08 7.30
5.73
Green 0.82 0.86 +0.14 4.90
None 1.01 1.06 +0.05 5.00
0.4 Orange 0.92 0.92 0.00 0.00
-0.00
Blue 1.00 1.00 0.00 0.00
None 0.89 0.84 -0.05 -5.60
0.6
Yellow 0.98 0.86 -0.12 -12.2
-12.8
None 0.98 0.84 -0.14 -14.3
Blue 0.93 0.82 -0.11 -11.8
0.8
White 1.13 0.86 -0.27 -23.9
-23.5
None 0.94 0.71 -0.23 -24.5
Blue 1.00 0.78 -0.22 -22.0
1.0
Green 0.66 0.55 -0.11 -16.7
-19.5
None 0.73 0.60 -0.13 -17.8
Black 0.71 0.54 -0.17 -24.0
*Calculated by the following formula:
(change in weight (g) / weight before (g) ) x 100
*Where I had two identical results for a certain concentration I chose this as the average as I thought this was more accurate and I ignored the other result and thought of it as an anomaly.
From this graph we can see the line of best fit steadily following a similar gradient and then towards the end moving to more of a straight line.
Conclusion:
From my results and the above graph I can see that at 0.4 molar there is no loss or gain in the weight of the potato- a 0% increase in weight. This shows that the concentration of the solution is the same as the concentration in the potato. From this I can conclude that the concentration inside the potato is 0.4 molar. These findings support
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