Objective:
To show the effect of surface-area-t0-volume ratio on the diffusion rate of hydrochloric acid.
Safety:
Hydrochloric acid is an irritant so eye protection should be worn.
Cut away from the body when using scalpels.
Equipment:
-Stained agar
-Scalpel
-4 test tubes
-Ruler/Callipers
-2M HCL
-White tile
-Stopwatch
Method;
1. Cut the stained agar into 4 different sized cubes (10mm, 7mm, 5mm, 1mm.)
2. Place into the 4 test tubes and label accordingly
3. Add 3 cm3 of HCL to each test tube and start the stopwatch immediately.
4. Time how long it takes for each cube to be entirely colourless and record the results.
5. The experiment should be repeated 3 times to ensure reliability.
To show the effect of surface-area-t0-volume ratio on the diffusion rate of hydrochloric acid.
Safety:
Hydrochloric acid is an irritant so eye protection should be worn.
Cut away from the body when using scalpels.
Equipment:
-Stained agar
-Scalpel
-4 test tubes
-Ruler/Callipers
-2M HCL
-White tile
-Stopwatch
Method;
1. Cut the stained agar into 4 different sized cubes (10mm, 7mm, 5mm, 1mm.)
2. Place into the 4 test tubes and label accordingly
3. Add 3 cm3 of HCL to each test tube and start the stopwatch immediately.
4. Time how long it takes for each cube to be entirely colourless and record the results.
5. The experiment should be repeated 3 times to ensure reliability.
Conclusion:
The results followed my prediction that as the surface area to volume ratio increased the time taken for the cube to become colourless decreased, this is shown by comparing the largest cube which had the highest surface area to volume ratio and took over 10 minutes to become clear to the smallest cube which had the lowest surface area to volume ratio and took 3 seconds to become clear.
3 factors I controlled in this experiment are the volume of HCL added to each cube, the concentration of the HCL, and the size and shape of the vesicle each of the cubes were placed in.
An additional procedure I could add to make my results more reliable would be to repeat the experiment multiple times and then average the results. I could also refine the technique used to measure the cubes to make the results more accurate.
Surface area to volume ratio is important to living organisms because it allows some organisms that are small enough to not need a respiratory system as their ratio would be low enough that the oxygen and CO2 could just diffuse into and out of the cell, it also allows for specialised respiratory systems to be created to ensure enough gas can diffuse around the body.
Limitations of this experiment would be that the HCL might not be found in that concentration in a living organism so the results would not be an accurate comparison to the conditions found in a cell, there is also no membrane so diffusion would not be very similar to living organisms.
The results followed my prediction that as the surface area to volume ratio increased the time taken for the cube to become colourless decreased, this is shown by comparing the largest cube which had the highest surface area to volume ratio and took over 10 minutes to become clear to the smallest cube which had the lowest surface area to volume ratio and took 3 seconds to become clear.
3 factors I controlled in this experiment are the volume of HCL added to each cube, the concentration of the HCL, and the size and shape of the vesicle each of the cubes were placed in.
An additional procedure I could add to make my results more reliable would be to repeat the experiment multiple times and then average the results. I could also refine the technique used to measure the cubes to make the results more accurate.
Surface area to volume ratio is important to living organisms because it allows some organisms that are small enough to not need a respiratory system as their ratio would be low enough that the oxygen and CO2 could just diffuse into and out of the cell, it also allows for specialised respiratory systems to be created to ensure enough gas can diffuse around the body.
Limitations of this experiment would be that the HCL might not be found in that concentration in a living organism so the results would not be an accurate comparison to the conditions found in a cell, there is also no membrane so diffusion would not be very similar to living organisms.