Osmosis
In my experiment, I plan to find out whether the concentration of sugar
in water
affects how much water will go in to a potato chip. I will do this
by having
twelve test tubes three with one molar of sugar solution, three
with ½ molar
sugar solution, three with ¼ molar sugar solution and three with
zero molar
sugar solution. I will do three of each so I can take an average
from the
results. Prediction For the investigation I think that the lower
the
concentration of sugar in the test tube the larger mass the potato chip
will be.
I think this because I know that Osmosis is the movement of
water molecules
across a partially permeable membrane from an area of high
water concentration
to an area of low water concentration. Therefore the
water molecules pass from a
high concentration (in the water itself) to a low
concentration (in the potato
chip). Therefore, the chips in higher water
concentrations will have a larger
mass than in higher sugar concentrations.
Diagram For Prediction This is a
diagram for what I predict will happen in
the experiment. If the potato is in
one Molar solution then the increase in
mass due to osmosis will be little, as
there is more sugar than water in the
solution. If it is in 0.5 Molar solution,
it should increase a little. If it
is in pure water then the increase will be
quite a lot, as there are many
water molecules in water, therefore due to
osmosis its mass will increase
more that the other two experiments. Fair Test In
the investigation, I will
make it a fair test by keeping the following things
the same: 1. Volume of
solution – 20ml 2. Same size boiling tube 3. Same type
of potato 4.
Temperature – Room Temperature 5. Same sugar solution 6. Same
size potato
borer 7. Time left for – 48hrs 8. Size of potato chip – 20mm For
all of these
criteria, having them not uniform in all of the tests would mean it
would not
be a fair test. For instance if I had a longer potato the surface area
would
be bigger and there would be more space for osmosis to occur. Apparatus To
do
this test I will need – 1. Twelve test tubes 2. Sugar solution 3. Water
4.
Twelve potato chips 5. Size 5 borer 6. Ruler 7. Two test tube racks 8.
A Knife
Diagram These are diagrams of how the apparatus is used. This
first one is about
boring the holes in the potato This one is the potato chip
in the water
solution. Method 1. Take about two or three potatoes and bore
twelve potato
cylinders out of them using borer size 5. 2. Cut the potato
cylinders to 20mm,
then set aside. 3. Collect twelve test tubes and put in
test tube racks. 4.
Measure 20, 10 and 15ml of water three times (3 x 20,
3 x 10 and 3 x 15ml water)
then 5. Measure 20, 10 and 5ml of sugar solution
three times (3 x 20 3 x 10 and
3 x 5ml sugar solution) 6. Mix these in
this order, 20ml water in three test
tubes. Three test tubes of 10ml water +
10ml sugar solution. Three test tubes of
15ml water and 5ml sugar
solution. Finally three test tubes of 20ml sugar
solution. 7. Attempt to put
all potato chips in at the same time. 8. Leave for
48hrs. 9. Come back in
48hrs time and take all the potato chips out of the test
tubes. 10. Roll them
carefully on paper towels or other absorbent material to
remove excess water.
11. Weigh each chip individually and record the
measurement. Results Molar
Mass at start Mass at finish Difference Increase in %
1.00 1.68 1.22
-0.46 -27.38 0.50 1.68 1.36 -0.32 -19.05 0.00 1.68 2.20 0.52
30.95 1.00
1.68 1.22 -0.46 -27.38 0.50 1.68 1.38 -0.30 -17.86 0.00 1.68 1.95
0.27
16.07 1.00 1.68 1.21 -0.47 -27.98 0.50 1.68 1.33 -0.35 -20.83 0.00
1.68
1.90 0.22 13.10 Graphs See attached sheets. Conclusion My results
show that the
mass of the potato in the experiment with one molar of sugar
solution decreased
by about -27.68 % which means Osmosis must have occurred
because the water
leaving the potato’s cells into the sugar solution
decreased the mass as the
sugar molecules can’t get into the potato as its
molecules are too big. The
potato that was in 0.5 molar sugar solution
decreased in mass by -19.25%.
Looking at the graphs you will notice that
the graphs show a positive
correlation. My results agree with my prediction
in the sense that they are
showing the same thing that I had predicted. Which
was, that the potato chip
would increase in mass when it was put into pure
water and would decrease in
mass when put into pure sugar solution.
Evaluation The method I used was
reliable. There were not any anomalous
results; this can be seen on the graph as
all the points on the graph
correlate well. If I could do this investigation
again, I would have repeated
the investigation five times because if you do an
experiment more times you
get a better average. I could have investigated a
wider range of variables
(i.e. 1, ½, ¼, 1/8, 1/16, 1/32) this would show
better the relationship
between sugar solution concentration and the amount of
osmosis occurring.