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Osmosis Coursework

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Introduction

Osmosis Coursework To investigate the affects of the concentration of the sucrose solution on the rate of osmosis. Aim: To find out how and why the concentration of the sucrose solution will affect the rate of osmosis. Hypothesis: Osmosis is the diffusion of water through a semi-permeable membrane, such as a cell membrane, the water will randomly move out of the high concentrated region to the low until it has reached a state of equilibrium. Osmosis A different plant cell will have a different cell membrane so the rate of osmosis will either increase or decrease. Introduction: I am going to investigate whether changing the concentration of sucrose (sugar) the sugar solution surrounding the potato cells will affect the rate of osmosis. Prediction: I predict that as the sucrose concentration increases the rate of osmosis decreases. This will happen because the sucrose solution being a lower concentration will move into the potato cell, which is lower concentration. So if the outside is a higher concentration of water than the potato, the water will move into the potato. As the sucrose particles inside increase the concentration of water will be lowered and the concentration of the sugar in the solution will increase. ...read more.

Middle

The temperature of water- a higher temperature will increase the energy in the solution therefore the particles will vibrate more so there is more chance of osmosis happening making it an unfair test. Equipment: Potato tissue- to be experimented on by placing in different concentrations of sugar solutions. Cork borer 6mm- to take out the potato tissue from the potato more accurately. Scalpel- to measure and put in the sugar solution. Sugar- to be dissolved in water as part of the solution. Water- in which the sugar will be dissolved in as part of the solution. Ruler- to measure the length of the potato tissue. Stopwatch- to measure the time in which the potato is allowed osmosis to happen when it is in the solution). Beakers- to put the solution and potato pieces in. Measuring cylinders- to measure the volume of water. Method: 1) Get all the equipment out. 2) Use cork borer to get a potato cylinder, and then use the scalpel to cut it in to lengths of 6cm. 3) Use distilled water in the first experiment. 4) Measure the weight of the potato and record it. 5) Insert the potato into the beaker with the pure water in it. 6) Wait for 5 minutes then take it out and measure it. 7) Repeat three times. ...read more.

Conclusion

Therefore less water could be diffused into the potato piece so there is less change in the mass than in a potato placed in a lower concentrated solution (i.e. 10%). This is as I predicted at the start of the investigation. Evaluation I think that the results I got were reliable because there were no anomalies. Using the standard error of the mean I found that there were only two inaccurate results which further supports the fact that the evidence are very reliable. If the were anomalous results they could have been caused by water loss in the tube or in the potato, therefore the concentration of water outside or inside would have change. Measuring mass instead of length is also better because the potato piece could have expanded width ways as well as length ways, also there could have been some air pockets in the potato which could have stored some water so not increasing the size at all. To make my investigation better, I could have had a wider range of the variables, for example the sucrose solution could be up to saturation point. Doing this is can see when there is minimum amount of osmosis happening and even when osmosis is happening but the water is diffusing out into the sucrose solution instead of onto the potato. ...read more.

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