Prediction
I predict that at the start of the investigation, the mass of the chip will increase, but later the mass of the chip will begin to decrease. This is because the water moves from a dilute solution to a more concentrated solution. This is known as osmosis.
The reason the mass of the chip gradually increases at the start is because there is a high concentration of water outside the chip and a low concentration within the chip. This causes the water to enter the chip by osmosis. The chip will weigh more after removal.
The chip then begins to decrease in mass because the sucrose solution has a lower concentration on water and the chip has a higher concentration of water. This causes the chip to decrease in mass as the water leaves the chip by osmosis. The chip will then weigh less after removal.
Apparatus
- Scalpel
- Tweezers
- 12 Beakers
- Scales
- Core-pore
- Potatoes
- Sucrose solution
- Ruler
METHOD
- Collect apparatus
- Cut out 12 potato chips with the core-pore
- Using a ruler measure 2mm on each chip and use the scalpel to cut it off at this point.
- Weigh each potato chip on the scales and take note of the weight on your table.
- Fill each beaker with 25ml’s of solution
- Put two chips into the sucrose solution of 0.0
0.2
0.4
0.6
0.8
1.0
7. Weigh the chips on the scales after leaving them for one hour in the solution.
8. Do it again
Test 1
Test 2
Average
Weight Change
Concentration (mol/litre)
Conclusion
My hypothesis was correct. From this investigation I noticed that at the start the mass of the chip increased and them it began to decrease towards the end of the experiment.
Analysis
My hypothesis was correct. From this investigation I noticed that at the start the mass of the chip increased and them it began to decrease towards the end of the experiment.
My results show that the potato chips increase in mass at the start of the investigation. When the sucrose concentration is at 0.0 the average change in mass is 13.13% and when the concentration of the solution is 0.2 the average change in mass is 5.635%. This suggests that the water is moving into the chip by the process of osmosis. The reason the mass of the chip gradually increases at the start is because there is a high concentration of water outside the chip and a low concentration of water within the chip. This causes the water to enter the chip by osmosis. The chip then weighs more after removal.
At concentrations above 0.4 the chip begins to decrease in mass, e.g. when the concentration is at 0.4 the average change in mass drops to –5.405%. This suggests that the water is moving out of the chip by the process of osmosis. The chip then begins to decrease in mass because the sucrose solution has a lower concentration on water and the chip had a higher concentration of water. This causes the chip to decrease in mass as the water leaves the chip by osmosis. The chip then weighed less after removal.
Evaluation
The graph that shows the average weight strongly resembles my prediction. This suggests that the experiment is fairly accurate.
The investigation could have been made more reliable by repeating the experiment more than twice.
The surface area of the potato chips were not all the same, the results would have been more reliable if they were all the same mass to begin with. This would have made it a fair test, as the sucrose concentration would have had the same surface area to react upon.
To provide additional evidence I could have included concentrations that increased by 0.1, this would have also increased the accuracy of my results. I could have also used different types of potatoes and sizes.
Safety
- Make sure all bags are under desks so no one is liable to trip or fall.
- Walk slowly as you may trip or collide with another person
- Be sure to hold scalpel appropriately as injury could occur.
- Be careful not to spill solution onto floor as someone may slip. If you do happen to spill the solution, be sure to clean it up immediately.
- Make sure you follow all the instructions of your teacher.
- Make sure all apparatus is put away in their proper place.
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Do not carry to many pieces of apparatus at once.
