Osmosis Practical Research Essay

The cause of this investigation was to the amount of salt that have to be added to 1 litre of water and prevent potato chips from absorbing or dropping water in a process called osmosis. It is believed that various degrees of salt concentration have an impact on osmosis activity in potato cells; hence as the attention increases, enhances the rate of osmosis should limit to a certain point. The experiment is aimed at assisting Mr. Chip, a potato chips vendor; determine how much salt he need to be adding to his potatoes to increase their fantastic during storage.
Hypothesis:
When potato chips of equal size and weights are inserted into an equal amount of salt solution of different concentration with constant pressure and temperature, the mass of the chips will decrease with the increase in the salt concentration of the solution. Eventually, the mass of the potato chips will reach appoint of no further change called the isotonic point. If the salt solution concentration continues to increase, the mass of the potato chips will start to decrease. Consequently, the change in mass of the chips becomes a negative value with water continuously getting out of the potato cells into the solution.

Osmosis is a type of passive diffusion that happens with water movement across a semi-permeable membrane. In this process, water molecules in a solvent move from an area of low concentration to an area of high concentration, with the concentration gradient. If the potato cells are in a hypotonic solution, the intracellular potato environment is more concentrated than the solution. After some time, the potatoes cell will gain mass because the water diffuses into the potato, causing the potato to be larger, otherwise known as turgid. If the potatoes are in a hypertonic solution the potatoes intracellular environment is less concentrated than the solution. This means that the potatoes will lose mass because the water diffuses out of the potato by osmosis, becoming plasmolyzed. The potatoes that are in the isotonic solution, meaning that the potatoes intracellular environment is the same concentration of the solution, do not change their mass. This is also known as flaccid because the same of amount of water comes in the potato as goes out.

Independent variable

The independent variable is the concentration of the salt solution.

Dependent variable

The dependent variable is the gain in mass of the potato. This shows the rate at which osmosis occurs.

Controlled variables

Same volume and source of water

Potato cube size and source

Time for osmosis to occur

Concentration of the solutes in the water

Materials:

Plenty of common salt. (Sodium chloride.)

Laboratory balances, beakers and basic lab equipment

6 test tubes and two beakers per student

Cork borers and blades to cut potato cylinders

Potatoes

Boiling tubes x 6 per students

Boiling tube racks

NaCl

Balances

Weighing boats

Beakers

Cork borers

Razor blades

filter paper

labels

white tiles

stopclocks

Method:

All the materials were collected.

The apron and the safety glasses were worn for safety consideration.

Eight cubes of potatoes were cut (for replication) with dimensions of 2cm x 2cm x 2cm.

The potato cubes were weighed on an electronic balance, and the weight was recorded.

Five beakers were filled with 150ml of tap water, ice water.

The concentration of each of the solutions was recorded by recording the amount of salt added.

The potatoes cubes were added into each beaker.

The stopwatch was used to wait for 25 minutes to measure the effect of osmosis on the different solutions.

After the 25 minutes, the potatoes were removed from the beakers and placed on the paper towel. The water was removed by rolling the potato three times.

The potatoes were placed on the electronic balance and then weighed to see their weight after 25 minutes of being in the solution and osmosis acting.

The formula was used(Before weight-After weight)/2:To find the average difference in weight of the potato cubes and the % change in mass

The results were recorded.

Safety Considerations:

Though the experiment was relatively safe, it is good to take precautions always when doing a practical. For instance, as a group, we should be careful of our fingers when we are cutting the potatoes into cubes and also when holding the knife. Make sure the blade is pointing down at your waist, to reduce accidents.

Set up Diagram

Results

Below is a table showing the concentration of the different solutions and weight after/before of the potato and also the average difference in weight of potato cubes.

Concentration/ mass of salt added

Weight of potato

Cube before

(g)

Weight of potato cube after

(g)

Average difference in weight (g)

Percent change in mass (%)

Cube 1

Cube 2

Average

Cube 1

Cube 2

Average

10g

6.6

6.2

6.4

6.8

6.3

6.6

+0.2

3.13

20g

6.4

8.1

7.3

6.7

8.4

7.6

+0.3

4.11

40g

6.4

6.8

6.6

7.4

8.1

7.8

+1.2

18.18

60g

6.6

8.1

7.4

7.2

8.7

8.0

+0.6

8.11

Discussion

The graph shows a linear trend line that indicates that as the salt concentration of each solution is increasing the percentage change in mass is increasing. Thismeans that the independent variable causes the dependent variable to increase. The weight of each potato cubes before and after being in each solution for 25 minutes was being recorded. The difference in the weights was used to calculate the rate of osmosis; an increase in weight would mean a higher rate of osmosis. The pattern of results showed that an increase in concentration did lead to an increase in the rate of osmosis. However, in the highest concentration, the increase was not linear as before; meaning random errors played an impact, or it can also be concluded that after a certain point, concentration no longer plays a significant role in the rate of osmosis. However, in general, it can be concluded that an increase in concentration does affect the rate of osmosis.

Conclusion

The purpose of this experiment is to find out what effect concentration has on the rate of osmosis of potato cells. It is believed that a higher concentration would increase the rate of osmosis.Unfortunately; my results did not exactly support my hypothesis because the highest concentration did not have the highest rate of osmosis. It can be concluded; that an increase in concentration affects the rate of osmosis; however, after a certain point (isotonic point); the effect of concentration is minimised.