The Effect of Sodium Chloride on a Potato Chip

The Effect of Sodium Chloride on a Potato Chip

To investigate what happens to a potato chip's weight when placed in

different concentrations of Sodium Chloride

INTRODUCTION:~

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Osmosis is defined as 'the movement of water molecules from an area of

high water concentration to an area of low water concentration, across

a semi-permeable membrane' (Collins, 1999). A semi-permeable membrane

is a membrane that partially allows liquid to pass through. In the

case of the experiment I am carrying out, the potato chips have small

holes in their membranes, which only lets some water molecules flow in

and out of the solution and potato chips depending on the

concentration of both.

In a high concentration of water the amount of solute (e.g. salt) is

low. This would be called a weak or dilute solution.

In a low concentration of water the amount of solute (e.g. salt) is

high. This would be called a strong or concentrated solution.

When two such solutions are divided by a semi-permeable membrane the

water will move from the area of high concentration to the area of low

concentration, until both sides are equal or have reached

'equilibrium'.

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Dilute Solution Concentrated Solution

Semi-permeable membrane

Text Box: Water Molecule

Text Box: Sodium Chloride Molecule

Plant cells always have a strong cell wall that surrounds them. When

osmosis takes place, and they soak up water, they start to swell.

However the cell wall stops them from bursting as it is made from

cellulose, which is very strong.

When plant cells are put into dilute solutions they become 'turgid',

which means hard. Turgidity is important in plants, as it is this what

makes plant stems strong and upright. Pressure inside the cell (when

in dilute solutions) rises, and eventually this pressure is too high

that no more water can enter the cell. The potato cells would increase

in length, volume and weight because of the extra water.