Potato chips experiment

Investigate the effects of different concentrations

of salt solution on potato cells

Introduction

Osmosis is the way in which many living things take up water (source:

GCSE Biology for You). During osmosis, water moves from a dilute

solution to a more concentrated solution through a semi-permeable

membrane. This membrane allows water molecules to pass through easily,

but does not allow solute molecules to do this. The movement of these

water molecules gradually dilutes the solution that had the higher

concentration until they are equal, or as close to equal as possible.

The following is a practical example that effectively demonstrates

osmosis.

Example A

Example B

% change in mass

Mass at start (g)

16.7

20.6

Mass at end (g)

11.8

25.2

From this example, we can see that example A reduced its weight by

4.9g, meaning that water molecules moved from the pure water into the

salt solution through osmosis. Similarly, example B gained 4.6g,

meaning that water molecules moved through the semi-permeable membrane

from the lower concentration of salt solution to the higher

concentration through osmosis.

Preliminary work

Apparatus

=========

à 3 galley pots

à 60 ml saturated salt solution

à 60 ml distilled water

à potato chips

à knife

à balance (accurate to 1d.p.)

à 50 ml measuring cylinder (accurate to 1ml)

à stopclock (accurate to 1d.p.)

Variables

=========

à Size of potato chip

à Time left

à Surface area of potato chips

à Age of potatoes

à Concentrations of salt solution

à Temperature of potato c...

... middle of paper ...

...lt that the balance I used was

accurate enough, and that the quantities were measured accurately.

However in future I could improve this accuracy by using balances

accurate to three decimal places and a digital syringe to ensure that

my quantities are exact. Therefore, my results are reliable and allow

me to draw an accurate and reliable conclusion. In the future, I could

extend my investigation by using different concentrations of salt

solution, for example ranging from 0-10% salt solution. I could also

use more concentrations in my experiment, which would give me more

results. This would then also give me a more accurate line of best

fit, and give me a more accurate measure of the salt concentration

inside the potato cells. Therefore, the reliability and accuracy of my

results and conclusions would be improved.