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  • Level: GCSE
  • Subject: Science
  • Document length: 2156 words

Investigate how osmosis affects the weight of potato strips.

Extracts from this document...

Introduction

Osmosis Investigation Aim To investigate how osmosis affects the weight of potato strips. Scientific Information Diffusion occurs when there is a high concentration of molecules in one place and a low concentration in another. This difference in concentration is known as a Concentration Gradient. Osmosis is a type of diffusion when water molecules move from a high sucrose concentration to a low sucrose concentration through a semi-permeable membrane. A cell membrane surrounds all cells. A membrane is very thin and forms a boundary between cells and their surroundings. Cell surface membranes control the amount of molecules moving in and out of the cell. They are partially permeable, which means they only allow small molecules through like water, oxygen and carbon dioxide and do not let bigger molecules pass through. The diagram above shows how small water molecules will pass through visking tubing but bigger molecules will not pass through. The water molecules will go to a more concentrated solution but because the sugar will not pass through the visking tube, the water will try and balance out the molecules present in the water. The visking tubing will then expand to allow more water in and will therefore have a bigger volume. ...read more.

Middle

(g) Average mass before (g) Mass after (g) (g) Average mass after (g) Average change in mass (g) % Change in mass 1 2 1 2 C 0.5 1.6 1.37 1.23 1.30 1.38 1.21 1.295 -0.005 -0.50 After I will do this experiment I will go on to doing my Main Experiment. Main Experiment Equipment List I will need to use a: * Scalpel ~ for cutting the potato strips * Corer ~ to core the potato strips * Potato ~ to conduct the experiment on * Tile ~ to cut the potato strips on * 25ml measuring cylinder ~ to measure how much water or sucrose is present * Beaker (cup) ~ to put the potato strips inside * Digital balance ~ to weigh the weight of the potato strips * Label ~ to label the cup with * Ruler (ascending in millimetres) ~ to measure the length of the potato strips * Rubber band ~ to hold the plastic on top of the lid over the cup * Plastic cover ~ to cover the cup and keep the moisture in * Sucrose ~ to mix with the water * Water ~ to mix with the sucrose * Paper towels ~ to dry off the potato strips * Permanent pen ~ to mark the potato strips Main Experiment Firstly I will draw my results table and get all of my equipment. ...read more.

Conclusion

Also not all the potatoes were taken out of the beakers at the same time because I took them out and dried them so some were left in the mixtures longer than others. I could have made this better by putting the potatoes in at 5-minute intervals. For example I could have put the potatoes in cup A at 12:20 and cup B at 12:25 etc. Although with my experiments I was happy with myself because I believe my results were quite accurate. I took every measurement to 2 decimal places and throughout the experiment I used the same type of potato. Another factor of my experiment that I would change if I were to do it again would be how I dried the potatoes. This is because I may have dried some potatoes more than other potatoes. I f I could change this I would put the potatoes on a tissue and place a fan 10cm away. I would then turn the fan on for 30 seconds to dry it before weighing the potato strip. With all these changes I believe I could improve my experiment and make the results more accurate. However I think that for my first attempt at doing this experiment my results have come out quite accurately. ...read more.

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