Osmosis

Osmosis Investigation

Introduction & Aims

At present I am investigating Osmosis, and I have devised a experiment to investigate the rate of it. I have been provided with potatoes, and all the common laboratory equipment.

I will look at 2 variables, one discontinuous, one continuous.

For my discontinuous veritable I have chosen TYPE OF POTATO.

I will have 3 different types of potato, chosen randomly, and numbered A, B & C.

For my continuous veritable I have chosen TIME.

Every 5 minutes, I will record the mass of the potato chip, along with the length.

I hope to be able to carry out this investigation, and produce some accurate results, to conclude my investigation.

My Hypothesis

I think that the rate of osmosis in each of the types of potatoes will be virtually the same. As some potatoes have a different texture, the results will not be exactly the same. I think the colour of the potato chip may have an influence on the rate of osmosis. From past experiments I think the each chip will lose on average around 0.25g in mass, and 4mm in length. The longer the potato is in the solution, the more the mass will rise until all the solution is absorbed into the potato.

Method

* I took 3 potatoes and labelled them A, B & C

* From each I cut a cylinder chip using a tool

* Using a ruler I made sure the length of the chips were the same

* I weighed each of the chips to the highest level of accuracy - (2 d.p.)

* I then measured the chips in mm

* I took 3 test tubes, for the chips A, B & C

* and filled each with 10cm3 of 1 molar sucrose

* I then inserted the correct chip in the correct test tube,

* and started the timer.

* Every 5 minutes I...

a. removed the sucrose & chip from the test tube,

b. dried the chip on a paper towel,

c. weigh the chip to the nearest 0.01g,

d. measured the chip to the nearest mm

e. reinserted the correct chip in the correct test tube,

f. poured the sucrose back in the test tubes,

g. and restarted the timer.

* This process continued for 25 minutes and was repeated five times

Results

Potato A Potato B Potato C

Minutes Mass (g) Length mm Mass (g) Length mm Mass (g) Length mm

0 1.18 30 1.18 30 1.18 30

5 1.15 30 1.14 30 1.15 30

10 1.12 29 1.09 29 1.11 29

15 1.05 28 1.06 28 1.06 28

20 1.04 28 1.01 28 1.04 28

25 1.02 27 1.00 27 1.03 27

Appearance Before:

A : Pale Yellow

B : Cream

C : White

Note: