Chardakov's Banana Experiment Essay

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Chardakov's Banana Experiment


The ability of water molecules to move is known as their water potential. Water molecules always move down a concentration gradient towards a region of lower water potential, that is, to where there are fewer water molecules, to where the water potential is relatively more negative.

As the water potential of one solution decreases, the density of the solution increases and as the water potential of a solution increases the density of this solution decreases. This would mean that if at all mixed, the less dense solution (i.e. the one with the lease negative water potential) would float on top of the denser solution (the one with the most
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For example, to make 0.8M solution, you add 80% sucrose solution, and 20% water. In this experiment, that would be 8cm³ sucrose solution, 2cm³ water. These measurements are specific because to make sure the test is a fair one, each test tube has to have the same amount of solution in it.

After this, cut up the banana into six pieces so that they are all as near to the same size as possible and small enough to fit into the test tubes. Put one piece of banana into one of the test tubes from each pair and then add one drop of Methylene blue stain to each tube that has a slice of banana in it and then gently shake each of these tubes gently to mix in the stain. Leave the experiment for a minimum of 20 minutes to allow the banana slices to soak.

After 20 minutes or so, take the square tipped needle and attach it to a small syringe. Take some of the stained solution from one pair and add one drop to the other test tube of that pair, which has the same concentrated solution. To insert the drop u place the tip of the needle into the middle of the solution and then push out one drop of the stained solution.

Now observe whether the drop sinks, stays in the middle or floats to the top.















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