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What affects the rate of osmosis?

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Introduction

Investigation: What affects the rate of osmosis The Problem Cathy works in a burger bar, making French Fries. She keeps the peeled chipped potatoes in water to stop them going brown before being cooked. She notices that they went soft if left in salt solution and hard if left in fresh water. Cathy needs to ensure that the chips are neither too hard nor too soft in order to make good French Fries for her customers. Factors that affect Osmosis Concentration of solution- it depends on the concentration of water in a solution to whether the potatoes will loose or gain water. Temperatures- the increase of temperature will make the water molecules; move faster so osmosis will happen faster. The size of the chip- the difference in surface area will effect how much water is lost or gained. The type of potato used for chip- each potato will have a different size of vacuole meaning that it can hold more water/less water than other potatoes Time the chip spends in a solution- the longer the chip is left in the solution the higher the chance of osmosis will take place. Introduction In this coursework I shall investigate what happens to the potato chips after they have been left in different concentrations of salt solution after a certain length of time. I will be comparing the various concentrations solutions with the potato chip to see if the concentration of a solution affects the rate of osmosis. ...read more.

Middle

that the size of the chips 3cm and the volume of solution, which was 5cm ,are appropriate and I wish to use the same amount of chip and volume of solution in the actual experiment. The distilled water gained mass (water) and each of the salt solution increased the loss of mass was greater. Looking for the osmotic potential I found that it must rest between distilled water and 0.5 salt solutions. Therefore I am going to repeat the experiment but using Distilled water, 0.1m, 0.3 0.4 and 0.5 salt solution. Fair test Given the mistakes made in the preliminary experiment there are a few areas where care is essential. There are also some constants, which must remain the same: * All of the potato slices must be placed in the solutions simultaneously. * All potato slices must be fully submerged. * All of the potato slices must remain in the solution for 48 hours. * The same potato will be used to bore slices out of. * Keep the temperature the same (room temp 23�C) * Make sure the concentrations are divided up carefully, using a measuring cylinder * Make sure the potato pieces are the same size Safety When conducting my experiment I will be making sure I don't harm my self or anyone else by always cutting up my potatoes on a ceramic tile. The use of the knife could be dangerous as there is a sharp blade. ...read more.

Conclusion

Problem with this method of experiment is that when we began the experiment the mass of each chip was not the same and neither was angle of each chip at the ends. I would also say that the chips and different amounts of time spent in each of the solutions, as they were not put into the solutions at the same time. The method we used to take of the excess water off was not accurate as we could have spent long on one individual chip, we could blot the chip too much or too less causing an anomalous results. To improve upon our method we may have used more potatoes to get the 18 chips as using just one potato meant that we had to be careful to not make mistakes when cutting the chips. We ought to have made sure prior the experiment that each of the chips mass weighed the same. We could have used a machine to cut the chips making the experiment a fair test and leaving no room for errors. We may have also rolled the potato chips on the paper towel a distance of 10cm for each, to remove the excess water. Furthermore we could have investigated between 0.1m and 0.2m salt solutions to find out exactly where the isotonic solution is, such as 0.11m, 0.12m, 0.13m, 0.14m and etc. We could investigate another factor for to work out an isotonic solution such as the type of potatoes used. ...read more.

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