Day 5: Graphing and Part 1/5 of the lab

Today we started of by constructing graphs out of class data and seeing how the best fit line works for all the data. The best fit line is pretty much the same for each graph. It intersects the x axis at the point of equilibrium when the solution in the dialysis tubing for example is the same molarity as the liquid outside.

Then we proceeded to do the rest of the Diffusion and Osmosis Lab.....

We did Part One with the starch and level of glucose. We put the dialysis tube which was originally clear and full of starch and glucose in the glass full of iodine and water. We saw a color change in the starch tube. Bits of the starch turned a dark blue color and looked like precipitate.

This lab part was a good example of Diffusion and Size. The starch molecules were too big so there was no real diffusion into the solution. But the glucose in the dialysis tube could go thru diffusion because it is small enough molecules to move.

We know the glucose got into the the water in the cup because we tested it with Benedict and saw a color change into orange.

The second part of the lab we took cubes of NaOH and added the element and the solution changed pink and then we let it sit. We took the cubes out later and spilt it in half. This is what it looked like:

Then we knew that some of the solution had gone into the cube of NaOH. If the white bit at the center is too big then it meant none of the nutrients of the solution didn't reach the nucleus. So therefore if the surface area was too big that is a indicator that the substance didn't soak up a lot.