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  • Level: GCSE
  • Subject: Science
  • Document length: 1026 words

An Experiment to find out the effect of osmosis on potato cells

Extracts from this document...

Introduction

An Experiment to find out the effect of osmosis on potato cells Plan Apparatus: * A borer * 25 test tubes * 5 test tube racks * 2 potatoes * A ruler * A sharp knife Variables: Four different sugar solutions at 10%,20%,30%and40% and distilled water Hypothesis: I hypothesis that the higher the sugar the less the potato size will increase. I think this because I think it will be harder for the liquid to get in because it is denser. Using the borer make cuts into the potato and pull out the pieces of potato. Chop the pieces so they are 20mm long repeat process 25 times. This experiment must be statistically viable i.e. the potato pieces must be identical. If you come to a bad piece of potato discard it. Put all the pieces into individual test tubes. Using one of the solutions fill up 5 test tubes to exactly the same height. ...read more.

Middle

The minimum pressure necessary to stop solvent transfer is called the osmotic pressure. Since the osmotic pressure is related to the concentration of solute particles, there is a mathematical relationship between osmotic pressure, freezing-point depression, and boiling-point elevation. Properties such as osmotic pressure, freezing point, and boiling point, which depend on the number of particles present rather than on their size or chemical nature, are called colligative properties. For dilute solutions the mathematical relationship between the osmotic pressure, temperature, and concentration of solute is much like the relation between pressure, temperature, and volume in an ideal gas. A number of theories explaining osmotic pressure by analogy to gases have been devised, but most have been discarded in favor of thermodynamic interpretations using such concepts as the entropy of dilution. Results: Table 1. Shows results gained (all lengths in mm) Solution Original Length Test 1 Test 2 Test 3 Test 4 Test 5 Average Distilled water 20 21 21 22 21 22 21.4 10% sugar 20 24 22 23 22 23 ...read more.

Conclusion

Evaluation: There could be many flaws with this experiment one of the main problems is the fact that the solutions I had to work with were previously made up. There is no guarantee that the solutions are what they are meant to be i.e. the labels could have been swapped. This could have been have been stopped if we had had the time and equipment to prepare these ourselves. The results also depend on where the racks are placed if they are placed in different areas in the classroom. Some may be in the sunlight or near a radiator this would cause the temperature to rise and may cause speeding up of the process. Another problem that may have occurred is the potato may not have been cut to exactly to the same sizes. These differences may not be visible to the naked eye. Or the potato may have been cut at an angle if the person chopping was not directly over the ruler and potato. Overall I do not think these problems affected our results to a great extent. ...read more.

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