Osmosis And Diffusion Lab : Experiment

2755 WordsOct 13, 201412 Pages
Osmosis and Diffusion Lab Saagar Chitale 10/13/14 AP Bio Pd.5 Introduction: The first part of this three part lab was an investigation that examined the relationship between rate of diffusion and the surface area to volume ratio. To simulate this, we used an agar cube with NaOH and phenolphthalein mixed in, and dropped it in an HCl solution. As the HCL diffused in and reacted with the phenolphthalein, we were visually able to see diffusion at work. Diffusion is the movement of molecules in a system from an area of higher concentration to lower concentration. This action keeps going until an equilibrium of molecules/ solutes is reached such that the overall movement of molecules through the barrier/membrane is 0. This however, does not mean that nothing is moving across the membrane. Though diffusion is often viewed as an orderly function of molecules moving from a high concentration gradient to a lower one, it is actually quite the opposite. The second law of thermodynamics states that the entropy- the randomness of molecular movement in the universe is infinitely increasing. This, in relation to diffusion in the cell means that if on one side of a membrane there is a high concentration gradient; there will be low entropy and less randomness of molecular movement. The 2nd law of thermodynamics suggests that the system will inherently try to increase the randomness. To do this, the side with the higher concentration will have to diffuse molecules to the other side of

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