This experiment’s ultimate goal is to find the water potential of the potato cell. This was achieved through placing potato cores in different concentrations of sucrose (0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 2.0%, 3.0% and 4.0%) solution and to observe how much water was gained or lost through osmosis to reach a prediction of the concentration within the potato cell. The results displayed that the concentration of sucrose within the potato cell is 1.7% and that as the amount of sucrose is increased in the external fluid, the less mass the potato will gain until the concentration is 1.7% - this is when the potato begins to lose weight. It was also shown that the rate of osmosis slows in the second 24 hour it is in the sucrose solution.
3.1 Background information
It is critical to understand how osmosis works through diffusion to reach equilibrium before studying how different concentrations of solutes affect the osmotic rate, and consequently, the mass of the potato – which is the purpose of this experiment. Explaining the osmotic movement of water is essential to understand how plants regulate their total fluid volume (J. Darnell. 2014).
According to HyperPhysics, diffusion is the result of particles intermingling due to their random kinetic forces that are absorbed by their surroundings. A distinguishing feature of diffusion is the mixing of particles, rather than mass movement. The particles move from a region of high concentration to an area of low concentration or move down the concentration gradient (BBC, GCSE BiteSize 2014). Osmosis is a type of diffusion where a spontaneous amount of water moves through a semi-permeable membrane from a region of low solute concentration to an area of high solute concentration in order to reach equilibrium; to become isotonic. To be isotonic means have an equal percentage of solute concentration of either side of the membrane which displays
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