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# An investigation into the effect of diffusion on the size of a cellWhat I am going to do is place some agar phenolphthalein in a HCl solution and time until the cubes go clear.

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Introduction

An investigation into the effect of diffusion on the size of a cell Introduction What I am going to do is place some agar phenolphthalein in a HCl solution and time until the cubes go clear. Theory Diffusion is the passive transport of how substances cross membranes. It is the movement of particles from of particles of a higher chemical potential to a lower one. In all diffusion the net flux of the particles transported is equal to physical property multiplied by the gradient. Diffusion happens because of the second law of thermodynamics; the entropy of closed system will always increase in time. Also substances being diffused go from a state of higher order to a state of lower order, so diffusion is a completely natural process for it requires no energy to happen. ...read more.

Middle

It also shows that my hypothesis is wrong, but I have already explained why. Surface area time to go clear (secs) rate of diffusion 0.25 107.72 0.009283327 1 196.47 0.005089836 2.25 231.72 0.004315553 4 267.75 0.003734827 9 278.39 0.003592083 Apparatus 5 cubes of agar-phenolphthalein; 0.5cm^3, 1cm^3, 2cm^3, 4cm^3, 6cm^3 250ml beaker 10cm^3 measuring cylinder mm rule Scalpel 100 ml of 2M HCl Distilled water It is necessary to have a rule that measures in mm to ensure the cubes are measured accurately, it is the same for using the measuring cylinder as this is needed for the precision it posses in making the solution of acid. Distilled water is needed to ensure the results are reliable as tap water contains number of things that will offer resistance to diffusion. Variables * The independent variable is the size of the agar cells, these will be made by cutting them up with a scalpel and measuring them to confirm, and I will have five different sizes and repeat the tests three times. ...read more.

Conclusion

Safety This experiment is particularly dangerous but a number of precautions should be taken, goggles and gloves should be worn when handling acid as it comes at quite a high molarity. A cutting plate should also be used when cutting up the agar cubes. Disposal of the agar should be in the bin. Method * Prepare agar cells using cutting plate and scalpel. * Measure cubes using mm rule and trim if essential. * Measure out 30ml into a test tube * Place the cubes in the beaker and then fully submerge them in the HCl solution. Start stopwatch. * Turn the blocks frequently over the time. * When blocks are clear against the piece of paper stop the stopwatch. Results Cell Dimensions (cm) Surface Area (cm^2) Cell Volume (cm^3) Simplest Ratio Rate Of Diffusion 0.5 3 0.125 24.00 1 6 1 6.00 2 12 8 1.50 3 18 27 0.67 4 24 64 0.38 6 36 216 0. ...read more.

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