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Investigation in Osmosis

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Introduction

Investigation in Osmosis Aim Aim: To carry out this experiment to find out whether a salt solution or a sugar solution is more efficient at the process of osmosis. We will do this by placing potato in jars filled with different concentrations of sugar and salt solution, then taking the weights of each before and after the experiment. From this we will be able to tell how much water has diffused either from the water into the potato or from the potato into the water in the process of reverse osmosis. Prediction: I predict that there will be a higher amount of reverse osmosis in the salt experiment. This is due to the fact that the sugar molecules are so much larger than the salt that there would be more salt particles in a certain space than there are in sugar concentration. So salt will create a higher potential. Reverse Osmosis: Here is a basic diagram show how when large molecules are present they create a change in water potential, and that this would lead to the movement of water from the 1.Sugar Experiment Each of the concentrations will be tested 3 times. ...read more.

Middle

mass of potato after test 1 +0.03 -0.06 -0.17 -0.09 -0.08 -0.08 -0.20 -0.25 Change in mass of potato after test 2 0.00 -0.03 -0.09 -0.06 -0.08 -0.12 -0.19 -0.31 Change in mass of potato after test 3 +0.14 -0.10 -0.16 -0.06 -0.05 -0.04 -0.02 -0.33 Percentage change in mass of potato after test 1 +2.50% -5.13% -14.66% -7.69% -7.77% -7.41% -16.81% -22.12% Percentage change in mass of potato after test 2 0.00% -2.54% -7.26% -5.56% -7.02% -8.96% -15.32% -25.20% Percentage change in mass of potato after test 3 +11.11% -6.90% -13.11% -5.36% -4.35% -3.36% -1.77% -29.73% Average percentage change +1.25% -6.02% -13.89% -5.46% -7.40% -8.19% -16.07% -23.66% Graph: Evaluation of Sugar Experiment: The graph clearly shows that as the sugar concentration increases there is a stronger amount of 'Reverse Osmosis' taking place. This is due to the size of the sugar molecules, and they're effect on the water potential. 2.Salt Experiment Method: 1. Set up apparatus as shown in diagram at the bottom of the page. - All vials will be the same. 2. Cut out a section of potato with the borer - a size 7 borer for every one will be used. ...read more.

Conclusion

3 +0.01 +0.02 -0.19 -0.19 -0.24 -0.18 -0.23 -0.32 Percentage change in mass of potato after test 1 +3.64% -11.67% -16.13% -25.40% -36.99% -40.63% -43.94% -44.78% Percentage change in mass of potato after test 2 +5.26% -2.94% -14.93% -25.76% -37.84% -44.83% -46.03% -44.44% Percentage change in mass of potato after test 3 +1.61% +3.51% -30.16% -30.16% -36.92% -29.03% -37.70% -47.76% Average percentage change +4.45% +0.29% -15.53% -25.58% -36.96% -42.73% -44.99% -44.61% Graph: Evaluation of Results: This graph shows that as there is a massive average percentage change in the Weight of the Potato, showing that here too there has been a very large amount of 'Reverse Osmosis' taking place. This is due to the size of the molecules and they're effect on osmosis. Conclusion: This graph proves that there was a greater amount of 'Reverse Osmosis' produced buy the salt solution. This is because for sugar or Glucose (C6M12O6) for 0.10m is 18g in 1ltr, and sugar doesn't dissociate. But Salt dissociates (NaCl Na+Cl- ) , effects osmosis because both ions attract water molecules. Therefore except for NaCl 0.10m when Salt has 2x the effect of 0.10m of sugar, Salt should always have a high water potential. James Routledge 11SAL 28/04/07 ...read more.

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