For this experiment I will be using the following equipment:
Measuring cylinders (2)
Glass Beaker (16)
Stop clocks (3)
Knife (1)
Potato (1)
Corer (1)
Tile (1)
Using the equipment above, the following experiment will be carried out:
A potato will be cut in half, and cylindrical shapes of potato will be cut out from one half of the potato using a corer. This will be done on a tile to ensure safety. The reason for only using one half of the potato is that, if only one half is used, someone else doing the experiment can use the other half. The cylindrical shaped potatoes will then be measured using a millimetre ruler, and they will then be cut, so that each potato chip is approximately 13mm long and 7mm in diameter. Each chip will then be dried using filter paper and weighed to check that it weighs 0.6gms. If it does not, it will be discarded and won’t be used. This is because the experiment has to be as fair as possible. Therefore the chips must all weigh the same before starting the experiment. After cutting and weighing the chips, the two measuring cylinders will be used to measure the 1M sugar solution (sucrose) and the water. Different amounts of each fluid will be mixed together, so that a 50ml solution is produced. For example, 30ml of sucrose, and 20ml of water. These will be mixed in a beaker, in which 1 potato chip will be added and left inside the beaker for 15 minutes. A stop clock will be started as soon as the chip is added. After 15 minutes, the solution will be carefully poured in to a sink, to ensure that none of it is spilt on the floor, increasing the risk of someone slipping. However the stop clock will not be stopped after 15 minutes, but only after the potato chip has been taken out of the beaker. This is because time never stops. The potato chip will be removed, dried in filter paper to remove any excess sucrose and water. This will ensure fairness of the experiment. The chip will then be weighed again to see if it has reduced in weight. The weight of the potato chip would be the most accurate to measure, and the most reliable of measurements to take, because a ruler is not accurate enough to detect any slight changes in length or diameter. However, an electronic scale can detect smaller changes. The results will be recorded and placed in a table, from which a graph will be produced. To get the most accurate and fair results it should be carried out at least 100 times. As there is not enough time, it will only be conducted twice. Below is a diagram showing how the experiment will be carried out:
I predict that, the more the sugar solution, the smaller the potato chip. The more the water, the larger the potato chip. This is because Osmosis is the passage of water from a weak solution to a more Concentrated solution. If there is more sugar in the solution, then the water will have to move from the potato chip to the solution to achieve equilibrium. If this is the case, then the chip will lose water and therefore decrease in weight. However, if there is more water in the solution, then the Potato chip would be more concentrated with sugar. This would mean that water would have to move from the solution, through the selectively permeable membrane to the potato. As the potato would be filled with more water, it would become heavier and increase in size and weight.
OBTAINING EVIDENCE:
Whilst carrying out the investigation, safety was taken in to account. The whole experiment was carried in the middle of the bench, so that the chances of anything spilling or breaking on the floor were reduced. Any spillages of sugar solution or water were cleared up, as someone could slip. The solution was removed from the beaker, at the end of the experiment, by pouring it in to the sink. This would also decrease the chance of spillages. Great care was taken when using the knife. This is because if the knife was left lying around anywhere, someone could trip and fall on top of the knife. An incident like this, could be life threatening.
For this experiment accurate measurements were taken. The experiment was carried out twice. For each experiment the following measurements were used:
One potato chip, weighing 0.6gms, was added to each of the solutions made using the measurements above. The sugar solution was 1M. After each experiment, the potato chips were dried and weighed. The results for both experiments were obtained and calculated to find the average. The data was then inputted in to the table below:
P.T.O.
As all of the measurements for the fluids were, multiples of 10, no more than 7 different combinations of solution could be made.
ANALYSING:
After looking at the table above, it can be seen, that as the amount of water in the solution increased, the weight of the potato chip decreased, and as the amount of sugar solution decreased, the weight of the potato chip decreased. This shows that the results undermine my prediction. For my prediction I predicted the as the amount of water increases the weight of the chip will increase too. However the table of results shows that as the amount of water increased, the weight of the potatoes decreased. Below is a graph showing the results from the table above:
Looking back at the scientific explanation at the beginning of the plan it can be seen that a potato is made up of 80% water and 20% solid matter. The starch makes up about 85% of the solid material. This would mean that there would be sugar in potato and that it is possible for Osmosis to take place. Looking at the table and graph it can be seen that Osmosis did take place, and that there was a difference in the weight of the potato after each experiment.
