An Investigation to Find the Effect of Changing the Sucrose Concentration on Osmosis in Potatoes.

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An Investigation to Find the Effect of Changing the Sucrose Concentration on Osmosis in Potatoes

Planning

        The aim of this investigation is to find out how the rate of osmosis in potatoes is affected by changing the concentration of the sucrose solution in which the potatoes are left overnight. This is how we did it :

Method

  1. Collect all apparatus necessary ready for use
  2. Use the cork borer to gain four equal sized pieces of potato
  3. Use a ruler and a scalpel to make sure the potato pieces are exactly equal. Weigh and record their masses
  4. Fill four test tubes with the different levels of concentrated solution and label carefully
  5. Add one piece of potato to each test tube
  6. Leave for 24 hours
  7. Gently pat dry, then weigh
  8. Record results
  9. Calculate mass gained/lost
  10. Redo experiment another 2 times.

Nb It is very important to try and be accurate when collecting results, so the results reflect what they are expected to. For these reasons, we used rulers to measure the length and width of the chips, and why we weighed the chips with a digital scale, which measured up to two decimal places.

Valid Evidence

To ensure that a valid test is carried out in this test, so that all the values are accurate, there are a few things you need to take into consideration. These are:

  • You need to ensure the temperature in the room is always the same.
  • The potatoes need to be the same size. In our case, they were all 2.9cm long and 1.1cm wide.
  • The same amount of solution needs to be put in each test tube. We used 20cm cubed in each test tube, which, in all cases but the 0% solution, meant 5cm cubed of the percent of solution with 15cm cubed of water.
  • The test tubes should be left in the same climate, with the same amount of light and heat.
  • The chips should be left for as close to the same time as possible.

Apparatus

To do this experiment once, you need all of the following apparatus:

  • Test tube racks
  • 4 test tubes
  • Diluted water
  • 5% concentrated solution
  • 10% concentrated solution
  • 15% concentrated solution
  • 20% concentrated solution
  • Scales
  • Ruler
  • Scalpel
  • Cork borer

Safety

As the only solutions we were working with on this experiment was sucrose solution, which is sugar dissolved in water, it did not matter if we got it on our skin. The only dangerous object we were using was a scalpel, and we were careful not to cut ourselves with this, and to use a board when we were cutting the potatoes so the blade did not cut the desk.

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Theory

To understand what is going on in this experiment, it helps to know some of the basic facts about what osmosis is. Below is some of my research on osmosis:

  • Osmosis can be regarded as a special type of diffusion.
  • Osmosis can be explained using the kinetic theory. Molecules of sugar and water ate continually moving and bombarding both sides of the partially permeable membrane. Sometimes, a water molecule passes through one of the tiny holes.
  • If there was pure water on both sides of the membrane, equal numbers of water molecules would flow in ...

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