Investigating Osmosis in Potatoes

Investigating Osmosis in Potatoes

Preliminary Experiment

Aim

The aim of this experiment is to determine the solute concentration of

potato tissue; i.e. To investigate at which point the sucrose

concentration is the same as the solute concentration inside the

potato (an equilibrium is reached)

Introduction

Osmosis is the movement of water molecules from an area of high

concentration; (a weak solution), to an area of low concentration; (a

strong solution), through a partially permeable membrane. My

experiment will prove that the concentration inside the potato is

lower than the concentration of the water molecules, outside the

potato if using distilled water or very low concentrations of sucrose

solution.

Preliminary Method

Cut two potato cylinders to the correct sizes e.g. 5cm in length, and

dry them out using paper towels. It is important to dry out the potato

cylinders because the excess water inside would have an effect on the

results, and this would therefore create an unfair experiment. Then

one must record their masses and lengths. Place them into the two

different solutions; 1.0M of sucrose solution and distilled water, and

leave them for fifteen minutes. One must leave the potato cylinders in

the two different solutions for at least fifteen minutes because this

is a minimum time, in which the starch particles will be able to

diffuse into the surrounding liquid, if indeed that is the outcome.

Then remove the potato cylinders and dry them out for a second time to

rid any excess water which is just clinging to the outside of the

potato cylinder, so that the only mass counted, is that of the liquid

which is inside the potato. Record their masses and lengths again. For

safety reasons I will be very careful when using the scalpel and

potato corer.

Equipment for my preliminary experiment

· One boiling tube with 30cm cubed of distilled water

· One boiling tube with 30cm cubed of 1.0M of sucrose solution

· Two potato cylinders, approximately the same mass and length