Essay Color Key

Free Essays
Unrated Essays
Better Essays
Stronger Essays
Powerful Essays
Term Papers
Research Papers





The Effect of Solute Concentration on Osmosis in Potatoes

Rate This Paper:

Length: 1106 words (3.2 double-spaced pages)
Rating: Red (FREE)      
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

The Effect of Solute Concentration on Osmosis in Potatoes

AIM: to find out the effect of solute concentration on osmosis in
potatoes. This is to find the equivalent osmotic potential. [IMAGE]

PREDICTION: Osmosis is the movement of water particles from a high
concentration to a low concentration through a partially permeable
membrane. Osmosis happens when a partially permeable membrane allows
small water particles to pass in or out towards a low water
concentration. To reach an equivalent osmotic potential the
concentration of water molecules has to be equal on either side of the
partially permeable membrane. This means there would be no mass
change. If you had a beaker of water that is distilled and filled a
visking tube with water and some salt the water molecules would move
through the visking tube with salt in. As in the visking tube it has a
lower concentration.

I predict that as the solute concentration increases the mass of the
potato will decrease. This is because the water particles move from a
high concentration to a low concentration. As the solute concentration
gets higher and the water concentration will get lower, therefore the
water particles will move out of the potato and in to the solution
outside because the concentration outside the potato is lower.

There fore the higher the solute concentration the more mass the
potato will lose.

SCIENTIFIC THEORY: Water molecules are in constant motion. As they
move they hit the membrane and create a pressure called the water
potential. Solutions with a low water potential have a high solute
(osmotic) potential. And solutions with a high water potential have a
low solute (osmotic) potential. Molecules of H2O (water) move by
osmosis until the concentration of H2O molecules is the same on each
side of the partially permeable membrane. This is the EQUIVALENT
OSMOTIC POTENTIAL.

Turgidity is when the water outside the cell has a higher H2O
concentration than the H2O inside the cell. Water enters the cell by
osmosis. A plant cells membrane is partially permeable. When the water
enters the cell the cell swells up and water pushes against the cell
wall. The cell then becomes completely full ( the cell wall stops it
from bursting) and it is TURGID. It has reached TURGIDITY. The reason
why water enters the cell is because the sap inside a plant cell has a
high solute concentration and a low water concentration.

PLASMOLYSIS occurs when there is little water left inside a cell
because it leaves. The cell then becomes flaccid and limp. When the
water leaves the cell and the cell becomes plasmolysed the cell
cytoplasm causes the cell membrane to pull away from the cell wall.
The vacuole also shrinks because of this.

Preliminary experiment

Equipment: 6 test tubes

Test tube rack

Pipette

Potato

Cork corer

Knife or scalpel

Salt solutions (0,0.2,0.4,0.6,0.8,1)

Distilled water

Electronic Scales

10 ml measuring cylinder

Method:

1) Label the test tubes with the salt solution that you are going to
add to them.

2) Get the test tube rack and place the test tubes in it. Add the
correct salt solution to the test tubes with a pipette. The salt
solutions should go from o molar, 0.2m, 0.4m, 0.6m, 0.8m and 1molar.

3) Core out a part of a potato with a cork corer

4) Cut up the part of the potato in to 6 pieces, making sure the ends
with skin on is not used and that the disc shapes are relatively
equal.

5) Use electronic scales to weigh the pieces of potato and note down
the mass to 2 decimal places and what solution it is going to be
placed in to.

6) Place the potato discs in to the solutions and leave them for 2o
minutes. This should give time for osmosis to occur.

7) After 20minutes take the water out of the test tubes making sure
the potatoes don't get lost. Using a pipette would be ideal as the
potato then wouldn't be losing any water.

8) Weigh the potato discs again and not the mass down for the correct
solution.

9) Write out results and work out the percentage weight loss. To work
out the weight loss you take the mass change and divide it by the
original mass and then times that answer by 100 and that will give you
the % change in mass. We do this so that we have an average reading
for each disc of potato in the different concentrations of solute
solution.

[IMAGE]

results:

Solute concentration

Weight before (g)

Weight after (g)

Weight change (g)

% change in weight

0molar

0.02

0.07

0.05

0.2molar

0.04

0.04

0

0%

0.4molar

0.01

0.01

0

0%

0.6molar

0.05

0.04

0.01

0.8molar

0.04

0.01

0.03

1molar

0.06

0.05

0.01

My results show that with no solute in the solution means that the
mass of the potato will increase. This is due to the water molecules
moving from a high water concentration to a low water concentration
through the partially permeable membrane of the potato. My second and
third results for 0.2 m and 0.4 m have shown no weight change so this
means they were at the equivalent osmotic potential. This means that
the concentration of H2o molecules on either side of the partial
permeable membrane of the potato is the same. After the third reading
the mass of the potato decreased this was due to osmosis happening in
the opposite way to which it happened in reading 1. The solute in the
water makes the water have a lower water concentration therefore the
water moves from the potato through the partially permeable membrane
and into the water. Giving the potato a lighter mass.

Variables:

v Length of time in the solution

v Volume of the solution

v Concentration of the solute

v Temperature

I am changing the concentration of the solute to see weather it
affects osmosis. The others must be kept the same otherwise the
experiment would not work and would not be fair. The length of time
will always be the same and instead of leaving the potato in the
solute for 15mins it will be left in for 24 hours to allow osmosis to
occur fully. The volume of the concentration must stay the same
otherwise there will be higher concentrations in some test tubes and
not others. The temperature must be kept the same because if its
hotter it will increase the rate in which osmosis occurs and it is
colder it would decrease the rate.

Safety: make sure goggles are worn just in case any salt solution
could enter the eyes. Be careful whilst using a scalpel or knife so as
not to cut yourself, and carry test tubes around carefully so that the
don't drop and smash.

Experiment:

Equipment: 18 test tubes

Test tube rack

Pipette

Potato

Cork corer

Knife or scalpel

Salt solutions (0,0.2,0.4,0.6,0.8,1)

Distilled water

Electronic Scales

10 ml measuring cylinder

Method:

10) Label the test tubes with the salt solution that you are going to
add to them. Do each solution 3 times.

11) Get the test tube rack and place the test tubes in it. Add the
correct salt solution to the test tubes with a pipette. The salt
solutions should go from o molar, 0.2m, 0.4m, 0.6m, 0.8m and 1molar.

12) Core out a part of a potato with a cork corer

13) Cut up the part of the potato in to 18 pieces, making sure the
ends with skin on is not used and that the disc shapes are relatively
equal.

14) Use electronic scales to weigh the pieces of potato and note down
the mass to 2 decimal places and what solution it is going to be
placed in to.

15) Place the potato discs in to the solutions and leave them
overnight. This should give time for osmosis to occur.

16) After a night take the water out of the test tubes making sure the
potatoes don't get lost. Using a pipette would be ideal, as the potato
then wouldn't be losing any water.

17) Weigh the potato discs again and not the mass down for the correct
solution.

18) Write out results and work out the percentage weight loss. To work
out the weight loss you take the mass change and divide it by the
original mass and then times that answer by 100 and that will give you
the % change in mass. We do this so that we have an average reading
for each disc of potato in the different concentrations of solute
solution.

How to Cite this Page

MLA Citation:
"The Effect of Solute Concentration on Osmosis in Potatoes." 123HelpMe.com. 24 Jul 2014
    <http://www.123HelpMe.com/view.asp?id=120686>.




Related Searches





Important Note: If you'd like to save a copy of the paper on your computer, you can COPY and PASTE it into your word processor. Please, follow these steps to do that in Windows:

1. Select the text of the paper with the mouse and press Ctrl+C.
2. Open your word processor and press Ctrl+V.

Company's Liability

123HelpMe.com (the "Web Site") is produced by the "Company". The contents of this Web Site, such as text, graphics, images, audio, video and all other material ("Material"), are protected by copyright under both United States and foreign laws. The Company makes no representations about the accuracy, reliability, completeness, or timeliness of the Material or about the results to be obtained from using the Material. You expressly agree that any use of the Material is entirely at your own risk. Most of the Material on the Web Site is provided and maintained by third parties. This third party Material may not be screened by the Company prior to its inclusion on the Web Site. You expressly agree that the Company is not liable or responsible for any defamatory, offensive, or illegal conduct of other subscribers or third parties.

The Materials are provided on an as-is basis without warranty express or implied. The Company and its suppliers and affiliates disclaim all warranties, including the warranty of non-infringement of proprietary or third party rights, and the warranty of fitness for a particular purpose. The Company and its suppliers make no warranties as to the accuracy, reliability, completeness, or timeliness of the material, services, text, graphics and links.

For a complete statement of the Terms of Service, please see our website. By obtaining these materials you agree to abide by the terms herein, by our Terms of Service as posted on the website and any and all alterations, revisions and amendments thereto.



Return to 123HelpMe.com

Copyright © 2000-2013 123HelpMe.com. All rights reserved. Terms of Service