Find out what affects the rate of Osmosis

My Aims

* I am aiming to find out what affects the rate of Osmosis.

* To do this I am going to use temperature as a variation and my aim is to use it successfully.

Prediction

I predict that the warmer the water, the faster the rate of Osmosis occurs. I believe that Osmosis will occur when the water is at 10 but when the water temperature increases to higher temperatures e.g. 50 I believe a greater amount of water will of passed through the Visking Tubing (a semi permeable membrane).

Equipment

* Visking Tubing

* 5x 400ml beakers

* 2x 100ml beakers

* 1 molar salt solution

* 5 paper clips

* Distilled water

* Vegetable oil

* Thermometer

* Stop watch

Procedure

* Fill a 400ml beaker with 300ml of distilled water at the specific temperature e.g. 100 . Use a thermometer to get an exact temperature. Do this for every specified temperature.

* Pore some salt solution into 2x 100ml beakers and make sure that they are 20 .

* Place some of the salt solution (25ml) in to some Visking Tubing and do this 5 times.

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1 for each beaker.

* Weigh the tubing and record it do this for each piece.

* Place into beakers and secure with paper clips.

* Add oil to stop evaporation and at the same time start the stop watch.

* Wait 20 minutes.

* Take out tubing, dry it off and weigh them again, then calculate amount of water which has passed through the visking tubing.

* If possible repeat entire experiment again and match results from each to gain better results.

* The variable temperatures that I will be using are 20 40 60 80 and 100 .

Diagram

Safety

When doing this experiment you must take the correct safety cautions.

* All stools to be underneath desks.

* Girls must have their hair tied back.

* Have plenty of space to perform experiments to avoid any accidents.

* If you drop a beaker tell the teacher and clear it away, picking up all glass with dust pan and brush.

Results from trials

Temperature of water

Weight of Visking tubing before (g)

Weight of Visking tubing after (g)

Total gain/loss

(g)

20

50

22.60

21.06

23.87

21.83

1.27

0.77

20

50

14.99

13.94

20

50

13.61

14.85

For the 2nd and 3rd experiment I changed it from sugar solution to salt solution because the sugar solution began to go mouldy. I also changed the amount of solution because the tubing didn't fit into the beaker properly.

Looking at the 1st experiment the colder the solution the faster Osmosis occurred because there was more water in the tubing by the end.

The only problem with these 3 experiments is that I left them too long so the experiment went wrong. The water temperatures would of changed so when I do my real practical I will have got my equipment already ready so I can do it in just 1 lesson.

New Prediction

Looking at experiment 1 I have changed my prediction, I predict that the colder the water the more water passes through the semi permeable membrane. But to prove this theory I am changing my temperatures. I am changing my temperatures from 20 30 40 50 to 20 40 60 80 100 .

I expect that 20 will have increased in weight by about 0.2g and the rest below this mark.

This prediction maybe wrong though because I left the experiments too long and so the water temperatures would have levelled out by the time I weighed them all, but we will see.

Table of results for the practical.

Temperature of water

Weight of Visking tubing before (g)

Weight of Visking tubing after (g)

Total gain/loss

(g)

20

13.64

14.70

+1.36

40

12.51

12.97

+0.46

60

13.47

14.54

+1.07

80

15.22

16.04

+0.82

100

14.04

15.37

+1.33

Repeat

Temperature of water

Weight of Visking tubing before (g)

Weight of Visking tubing after (g)

Total gain/loss

(g)

20

10.26

8.65

-1.61

40

9.88

6.96

-2.92

60

10.20

9.85

-0.35

80

9.74

9.27

-0.47

100

10.44

10.03

-0.4397

Results for experiment 1.

Temperature of water

Weight of Visking tubing before (g)

Weight of Visking tubing after (g)

Total gain/loss

(g)

20

13.64

14.70

+1.36

40

12.51

12.97

+0.46

60

13.47

14.54

+1.07

80

15.22

16.04

+0.82

100

14.04

15.37

+1.33

My first experiment wasn't as successful as I would of hoped because the water temperatures weren't kept at the same temperatures during the practical. The 100 80 changed by -10 so the rate of Osmosis would of changed. I left the experiment for 20 minutes so that I could get results in one lesson. I believe that due to the temperatures changing the results maybe wrong because the results are a little different to my trials and I think that when I do my second experiment I will try to keep it at a constant level. I used a 1 molar salt solution because in my trials I used sugar solution but went off and so the trials failed so that's why I used the 1 molar salt solution.

I am going to do my experiment again to see if my results are roughly the same. According to my prediction the colder the water is the faster it occurs is correct but I must repeat at least once more to see if this prediction is 100% correct.

But if I compare my trials to my 1st experiment I can see that the experiment maybe correct and that 60 and 1000 results maybe incorrect due to the variations that the experiments experienced and so this is also another reason that I am going to repeat this experiment to see if the results are accurate.

Results from experiment repeat

Temperature of water

Weight of Visking tubing before (g)

Weight of Visking tubing after (g)

Total gain/loss

(g)

20

10.26

8.65

-1.61

40

9.88

6.96

-2.92

60

10.20

9.85

-0.35

80

9.74

9.27

-0.47

100

10.44

10.03

-0.4397

This experiment was a total mock up because I prepared this a day before and over night the visking tubing leaked and lost a lot of it's weight but I didn't think about changing the before weight and continued with the experiment that's why the results are totally wrong and I ran out of time. I also believe that someone changed the labels around which were on the visking tubing and that's why some have a higher loss than others.

Looking at my first prediction and my results I see that the prediction is still correct, Osmosis does occur faster when solution is in a warmer environment. So I shouldn't have changed my prediction it was right all a long. Looking at this table above shows that the warmer the solution is the less water seems to have been lost. So maybe it wasn't as bad as it could have been.

Analysis

Looking at the graph A1 the trend is that every other temperature variation that I used has a high percentage increase. But I think that the results were incorrect and so the graph will not be consistent with my prediction. Looking at all the evidence I have got, I believe that my prediction is correct but my results are wrong due to my careless mistakes which I made. The results force my prediction because I said that osmosis occurs faster when in a warmer environment and according to my results I was correct.

I believe that there are 2 anomalies in my first experiment which show up on my table. They are 20 and 60 ,these have affected the results and that's why there isn't a very good straight up sloped line on my graph.

Evaluation

During my trials I found out that there would be a problem with keeping the water temperatures constant. This was so the experiment would have been a fair test. But I did not act on this because I thought that if I continued to add water it will keep the water at around the right temperature. So I did my experiments and my idea totally failed. The 100 experiment and 80 experiment decreased by around 10-15 during the experiment so these results particular are totally incorrect.

The entire experiment followed my prediction but did not follow a line of best fit and so weren't very accurate.

I could really improve this practical a lot firstly by controlling the water temperatures by using water baths but I would have had to of used several water baths (one for each beaker). To stop the visking tubing from leaking I think I would of used a more expensive semi permeable membrane because the visking tubing which we used exploded under to much pressure from the water passing through the membrane.

I could improve my results by repeating the experiment several more times to work out a good average but we did not have the time to do this. I could take this experiment further by using more temperature variations to get a better picture and so better results at the end of it.