The Effect of Different Concentrations of Sucrose On Visking Tubing
Preliminary Work:
I am going to investigate the effect of different concentrations of sucrose on visking tubing
Apparatus:
* Measuring balance (used to measure the weight of the visking tubing)
* 18 beakers (containing varying concentrations of sucrose)
* 18 Visking tubing (containing sucrose solution of unknown concentration)
Diagram:
Method:
* I will gather the equipment in my apparatus list
* I will measure the weights of the visking tubing before they are put in the beaker. I will record the results
* I will put the visking tubing's in the beakers and leave them to react overnight
* I will take out the visking tubing and dry them, so no liquid will be left on it to effect the weight. I will then measure its weight on the measuring balance and record these results.
* I will then work out the mass and percentage change
Results:
Solution
(ml)
Number
Original mass (g)
Final mass (g)
Mass change (g)
Percentage change (%)
0.0
2
3
Average
0.2
2
3
Average
0.4
2
3
Average
0.6
2
3
Average
0.8
2
3
Average
.0
2
3
average
Aim:
To investigate the effect of osmosis in plant cells
Apparatus:
Electric Balance,
Borer,
Scalpel,
Potato,
Test tubes and racks,
Ruler,
Paper Towel
Safety Goggles,
Rubber gloves,
Sucrose
Diagram:
Method:
I will measure out 18 identical potato lengths, after I used the borer to get them from the potato. I will then weigh all of the potatoes and record the masses. I will then put the each potato in the sucrose solution in a test tube. Each solution will have 3 potatoes, so there will be 18 test tubes full of the sucrose solution and potatoes. When I return, I will remove all the pieces of potato, and dry them with paper towels. I will then measure them again and record. I will then work out the mass change and percentage change. I will record my results in a table like this.
Solution (M)
Number
Original mass (g)
Final mass (g)
Mass change
Percentage change
Prediction:
In my experiment, I am going to determine whether increasing levels of sucrose effect the mass of potato cells. I will do this by completing the experiment with different concentrations of sucrose. As the water from the cell is released from the cell, it will osmose through the membrane into the solution. Another outcome is that the water in the solution osmoses into the cell. The final outcome is that there is no osmosis taken place in. ...
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Solution (M)
Number
Original mass (g)
Final mass (g)
Mass change
Percentage change
Prediction:
In my experiment, I am going to determine whether increasing levels of sucrose effect the mass of potato cells. I will do this by completing the experiment with different concentrations of sucrose. As the water from the cell is released from the cell, it will osmose through the membrane into the solution. Another outcome is that the water in the solution osmoses into the cell. The final outcome is that there is no osmosis taken place in.
Water can either stay where it is or move to the other side, depending on where it is and the solution of the potato. So it will gain weight, lose weight, or stay the same. I predict that in the lower concentrations, the potato will gain weight as the concentration is likely to be higher in the solution than in the potato. In the middle concentrations it will have a point where it will gain or lose little, or either stay the same, this is the concentration of the potato. I predict that the higher concentrations will lose weight, as the solution is lower than that in the potato.
Water and Sucrose are present in potato cells, our potato cells being of fixed 8mm diameter as that is diameter of the borer. The potatoes are protected by a partially permeable membrane, which allows small molecules to pass into it, such as water, but not larger molecules like Sucrose. Therefore, only water can pass in this reaction.
Safety:
For a fair experiment, and to be safe, safety procedures have to be performed. Some safety methods, that I will perform, are to wear safety goggles, whilst observing the reaction. Also, I will use safety mats, in case any of the solution will splash onto the table. Finally, I will use rubber gloves at all times, so my hands will not be covered in the solution, when I am taking the potato out of the beaker.
Variables:
Controlled variables
* Concentration of sucrose in the potatoes,
* The diameter is fixed at 8mm
* The temperature is constant
* Time is a constant
Uncontrolled variables
* Concentration of sucrose in solution
* Weight of potato
Making it fair:
Each concentration of the solution, will be done three times, and there will be an average, to improve accuracy. There will be 6 different solutions, (0.0M, 0.2M, 0.4M, 0.6M, 0.8M, 1.0M).
Results:
Solution (M)
Number
Original mass (g)
Final Mass (g)
Mass change
Percentage change
0
3
3.64
-0.64
82.4175824
2
3.24
3.75
-0.51
86.4
3
3.41
3.9
-0.49
87.4358974
AV
3.22
3.76
-0.54
85.6382979
0.2
3.05
3.15
-0.1
96.8253968
2
3.2
3.31
-0.11
96.6767372
3
3.21
3.33
-0.12
96.3963964
2.73
2.65
3.26
-0.61
81.2883436
0.4
3.17
2.65
0.52
19.622642
2
3.28
2.73
0.55
20.14652
3
3.38
2.95
0.43
14.576271
AV
3.28
2.78
0.5
17.985612
0.6
2.95
2.07
0.88
42.512077
2
3.41
2.41
41.493776
3
3.29
2.36
0.93
39.40678
AV
3.22
2.28
0.94
41.22807
0.8
3.35
2.21
.14
51.58371
2
3.09
2.04
.05
51.470588
3
3.24
2.08
.16
55.769231
AV
3.23
2.11
.12
53.080569
3.2
.9
.3
68.421053
2
3.31
2.08
.23
59.134615
3
3.14
.75
.39
79.428571
AV
3.22
.91
.31
68.586387
These are my proper results.
This is my graph.
Analysis:
Looking at my results, I can conclude that the small concentrations lose weight, the middle concentrations stay the same, and the high concentrations gain weight. The shape of my graph line shows the mass change to be proportional to the solution. My prediction is therefore correct.
From my graph, you can see the change in mass is affected by the solution. I can also say that the concentration of sucrose in the cells is just below 0.3 moles. I found this out from my line of best fit, as the point in which it crosses is the concentration of the Cells. This is because the solution is isotonic to the cells and therefore no weight is gained or lost.
Evaluation:
I believe that my method was done well and produced reliable results. I repeated my experiment 3 times to improve accuracy. When measuring the potatoes, a ruler and a scalpel were used to cut it accurately. The cork borer was used to cut the potato chips, so they were all the same diameter. The cutting of the potato was therefore measure to + or - 1mm.
The shape of my graph shows definite correlation, but not direct proportionality. I believe that it should of being directly proportional but, my results were inaccurate in some places. All my points are close to the line of best fit, but they are not all on it. This shows that my experiment was quite accurate, but not accurate enough so they are all on the line of best fit. I had some slightly anomalous results and circled them on the graph. The reasons for the anomalous results could be;
* The timing of the experiment could of being different for each potato affected the results,
* Parallax error could be committed when cutting the potato.
* There may be different concentrations of sucrose in different cells of the potato,
* I could further my work, by weighing the test tubes to see how much they have gained or lost, so I can measure both the potato and the test tube to fin the mass change.
* I could also further my work, by using different organic cells, like animal cells etc.
My graph does support my conclusion as I mentioned in my analysis. I said that the small concentrations lose weight, the middle concentrations stay the same, and the high concentrations gain weight. This statement was correct as that is what happened.
Alan Carrara 11T Osmosis- Biology Coursework