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How Do Living Things Resist Change in pH
Transcript of How Do Living Things Resist Change in pH
By Kyla, Elizabete,
This lab was made to test if living organisms resist change in pH level. This was done by taking the pH levels of water, buffer, 10% liver, and 10% pumpkin solution as we add 30 drops of 0.1 HCl or 0.1 NaOH and taking the pH level after every 5 drops. It was concluded that organisms don't show a drastic change in pH, meaning that they have a buffer inside of them to protect them from drastic pH changes which could kill them.
Substances that prevent harmful changes in pH by giving H+ atoms to basic solutions and taking away H+ atoms from acidic solutions- meaning it prevents drastic changes in pH.
A chemical compound that releases H+ to a solution- when added pH level goes down.
A chemical compound that releases OH- to a solution - when added pH level goes up.
Does the pH of the cow liver and pumpkin solution buffer or does it have a drastic pH change.
Number of drops (HCl/NaOH) added each time (5), size of big and small beakers, amount (25 mL) of liver/buffer/pumpkin solution/water, and pH probes.
The constant must remain a constant because otherwise the data will be inaccurate and someone trying the experiment will have a different results.
Do living things resist changes in pH? The purpose of this lab is to see if the cow liver and the pumpkin solution or any other living thing have a buffer inside of them to prevent the possible drastic changes in pH that could kill them.
If you add a base (0.1 NaOH) or acid ( 0.1 HCl) to the blended cow liver and the 10% pumpkin solution, then it will buffer preventing drastic changes in pH. This is because all living things have a buffer, otherwise they could not resist any changes in the environment and they would eventually die.
1. Wash beaker thoroughly
2. Blend 25 mL of 10 % cow liver and pour into a 50 mL beaker and put it in a big beaker
3. Take original pH level and record it in your data table
4. Put 5 drops of 0.1m HCl (acid) in the cow liver, record indicated pH level
5. Add another 5 drops and record pH level
6. Keeping adding 5 more drops and recording with pH probes until you get to 30 drops
7. Wash beakers to get rid of HCl
8. Now repeat steps 1-6 except this time add 0.1 NaOH (base)
9. Do 3 trials of Hcl and NaOh in water and record data
10. Wash beakers thoroughly
11. Pour 25 mL of tap water into a 50 mL beaker and put it in big beaker
12. Repeat steps 1-9 with tap water
13. Pour 25 mL of buffer into a 50 mL beaker and put it in big beaker
14. Repeat steps 1-9 with buffer
15. Pour 25 mL of 10% pumpkin solution into a 50 mL beaker and put it in big beaker
16. Repeat steps 1-9 with 10% pumpkin solution
10% cow liver, 10% pumpkin solution
Water and buffer
The procedure will verify the hypothesis because the cow liver and pumpkin solution that are being tested will be compared to the buffer and water to see how the pH level changes. Does it buffer or does it have a drastic change in pH (water) ?
Always wear goggles. Wash hands to get rid of any chemicals. DO NOT TOUCH YOUR EYE IF YOU TOUCHED ANY CHEMICALS. Wash your eye of any chemicals if made contact and clean up your station.
Liver, water, pumpkin solution,buffer,0.1 Hcl, 0.1 NaOH
The errors in this experiment were when the pH went in the opposite direction or shared a different pattern than intended pH level. This could be a result from the pH probes used. An example would be in trial 1 buffer NaOH. Instead of the pH level going up it dropped down, with a starting pH of 7.65 and an ending pH of 5.56. Another error is that there was not a lot of trials in the experiment. If more trials were to be done then there would be more evidence to prove the point.
•Two 50 mL beaker and 2 large beakers
•2 pH probes
•Granulated cylinder - 25 mL
•25 mL of H2O
•25 mL of 10% pumpkin solution
•25 mL of buffer
•25 mL of 10% cow liver solution
- Total Change in pH ( |Final pH - Initial pH| )
- Average pH per number of drops added
(pH from each trail per each number of drops added together and divided by 3)
In conclusion, the hypothesis was partially supported. It was predicted that if you add a base (0.1m NaOH) or acid ( 0.1m HCl) to the 10% blended cow liver and the 10% pumpkin solution, then it will buffer preventing drastic changes in pH. This is because all living things have a buffer, which controls the pH level from changing drastically, and without a buffer the effects could be drastic. In the experiment the average change in pH for the water when the acid was added was -2.33, when the base was added the average change was +1.971. For the buffer the average change in pH when an acid was added was -0.224 and for the base the average change was -0.733. The liver had an average change of -0.496 when an acid was added and an average change of +0.787 for when the base was added. For the pumpkin solution the average change in pH with the acid added was -2.084 and when the base was added the average change was 3.183. The hypothesis was partially supported because as shown by the data the liver solution did buffer, where as the pumpkin solution did not. We know the liver solution buffered because just as the buffer was very slight compared to for example the water. This occurred because the liver is part of an organism and organisms have natural buffers within them and that is why the pH change was not drastic. The pumpkin solution should have hypothetically buffered too because a pumpkin is part of a plant which is an organism but it did not buffer due to the fact that it was only a 10% pumpkin solution in which 10% of the solution was the pumpkin and the other 90% was water and we know and as shown by the data water does not buffer and is drastically affected by changes in pH. With having the solution consisting 90% of water, the 10% that did buffer can not really affect the buffer the whole solution will have. For both the acid and the base the pH level changed after the drops were added, but when an acid was added the pH went down and when the base was added the pH level went down, though that was not true for the base trial.
If you add 0.9 NaOh or 0.9 Hcl to the 90% liver and 90% buffer solution then it will buffer preventing any drastic change in pH because living organisms have a buffer inside of them in which they can't live without if any drastic pH changes were to happen to them.
The purpose of this lab is to see if any drastic change would happen to the 90% liver and 90% pumpkin solution because we are using a stronger base and acid- 0.9 NaOh and 0.9 Hcl
The changes in procedure are instead of using 10% pumpkin and 10% liver solution you are using 90%. You are also using 0.9 Hcl and NaOh instead of 0.1.
In the experiment in the trial for the water the three original pH levels for the trials in which the acid was added were 7.76, 5.06, and 6 and after adding 30 drops of HCl the pH levels decreased to 4.58, 4.61, and 2.63. After adding 30 drops of NaOH it went from 6.8, 6.32, and 6.37 to 7.9, 7.75, and 9.75. For the buffer in the acid trial the pH levels went from 6.02, 6.05, and 6.02 to 5.52, 5.99, and 6.02 and for the base it went from 7.65, 6.15, and 6.13 to 5.56, 6.07, and 6.1. For the liver it went from 6, 5.27, and 6.11 to 5.3, 5.38, and 5.21 for the acid and from 6.3, 6.46, and 6.26 to 6.98, 7.28, and 7.12 for the base trial. For the pumpkin solution it went from 6.6, 6.6, and 6.83 to 4.99, 4.35, and 4.44 after the acid was added and from 6.65, 6.34, and 6.26 to 9.71, 9.46, and 9.63 after the base was added. The average change in pH for the water when the acid was added was -2.33, when the base was added the average change was +1.971. For the buffer the average change in pH when an acid was added was -0.224 and for the base the average change was -0.733. The liver had an average change of -0.496 when an acid was added and an average change of +0.787 for when the base was added. For the pumpkin solution the average change in pH with the acid added was -2.084 and when the base was added the average change was +3.183. The pH level increased for each solution when a base was added but when an acid was added the pH decreased. This was not true though in the trial with the buffer. When the base was added the average change in pH did not increase, as it would typically happen when a base is added the average pH decreased from 6.643 to 5.91, just as if an acid was to be added.
(Neil A. Campbell, 2007)
Average Changes in pH
When an Acid is Added!
Average Changes in pH
When an Base is Added!