# Water Potential Lab Report

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Water potential is often represented by the Greek letter, psi ψ .The higher the rate of collisions of the water molecules with the membrane, the greater the pressure on it. This pressure is called water potential. Water always moves from higher water potential to lower water potential. The standard unit for water potential is kilopascals (kPa), which is also the unit pressure. Pure water is designated a water potential of zero which has the highest water potential under atmospheric pressure at 25°C. (Source by: Understanding Biology for Advanced Level Third Edition, pg 441). The water potential of a cell is the overall tendency for water to diffuse into the cell by osmosis. There are two factors that affect the water potential of a plant cell, which are solute potential and pressure potential. Water potential can be calculated by using the formula below:- Ψ cell = ψs + ψp Solute potential in the plant cell is the…show more content…
The percentage difference in mass is calculated at the end of this experiment determining the changes in mass of the potato pieces and a graph is plotted. When the potato is placed in the distilled water and 0.2 moldm-3 sucrose solution, the water will diffuse into the cell sap by osmosis. This increases the mass of the potato pieces. The cell sap of potato cell will lose water by osmosis and therefore decreases the mass of the potato pieces when it is placed in a solution with a more negative solute potential which are 0.4 moldm-3, 0.6 moldm-3 and 0.8 moldm-3 concentration of sucrose solution. The point where the water potential in the potato cell is equal to the solution potential of the external solution can be determined by obtaining the value where the curve cuts the horizontal axis of the