Potato Experiment Osmosis Experiment

Introduction

Osmosis is the diffusion of water across the semi-permeable membrane from a region of low solute concentration to an area of high solute concentration in order to equalize the level of water in each region. Hypertonic, hypotonic and isotonic solutions are involved in this process. Water tends to move from a high to low concentration area, towards a higher solute concentration is hypertonic. When there is more solute outside of a cell, the cell is hypotonic, and when there is more solute inside a cell, the cell is hypertonic. When the solution concentration is equivalent to the concentration of the solution inside the cell, it is called isotonic. Osmotic pressure is the pressure difference needed to stop the flow of solvent across

Temperature is really important factor during this experiment because osmosis requires certain temperature. The higher the temperature is the faster the rate of osmosis, this is because the high temperature gives the particles from the solutions more kinetic energy. We did an experiment on a potato rods to determine the osmotic pressure of some potato cells. We used different type of solution, 0.0 M (distilled water), 0.15 M sucrose, 0.35 M sucrose, and 0.50 M sucrose, then we placed the potato rods in the 4 Petri dishes of solutions.

First, we got a potato, and we used a cork borer to cut narrow eight rods from the middle of one potato that it is about 50-77 mm long. Then, we cut the ends of the rods square and placed them on a paper towel to dry for about 5 minutes from the water that we rinse it in. Then, we got a 4 Petri dishes and started to label the top and bottom as the follows: 0.0 M (distilled water), 0.15 M sucrose, 0.35 M sucrose, 0.50 M sucrose. And we filled them with the appropriate solution. Then, we used a ruler to measure each rod and placed 2 into each Petri dish so we could measure them again at the end of the experiment. The potato rods were immersed in the solution for an hour, then we removed them, blot dry and measured them

The percent change in mass of the potato cells is positive when incubated in a concentrations of 0.00 M, and 0.15 M of sucrose. These 2 concentrations are hypertonic. Then the percent change in mass of the potato cells in negative when incubated in concentration of 0.35 M, and 0.50 M of sucrose and these concentrations are hypotonic. We calculate the percent change in length by subtracting the first measurement length from the second measurement length, then divide them by the original length then we multiply by 100. Example: 69-76/76*100 = -9. The osmotic equation is 22.4(M)(T)/273 atmosphere. The 22.4 is the osmotic pressure in the atmosphere, M is the molarity of the solution where no change in length, and T is the ambient temperature in Kelvin: K= ° C +