Agar gel lab report

Fair Test:

• There should be minimal error in measuring the dimensions of agar gel used for each reading.
• The agar gel should be dropped in the test tube or beaker as soon as the stopwatch is started.
• The agar gel sample in the dish should be closed with a lid after measuring the dimensions, so that the agar gel is appropriate for use.
• The graph paper should be clearly visible under the dish to take accurate dimensions.
• It should be made sure that the stopwatch is stopped when the pink colour has disappeared from the agar gel.
• It should be made sure that the surroundings are constant in the area where the experiment is being conducted.
• All the readings must be taken at eye level, i.e. the dimensions should be read at eye level, so that mo parallax errors take place.
•  It should be made sure that the apparatus is in good use so that inaccurate results do not take place and therefore lead to anomalous results.

SAFETY PRECAUTIONS

• You should take care while using glass equipment like, beakers and measuring cylinders as any broken piece of glass should not be handled with bare hands as it can cause severe injuries..
• While cutting the dimensions with a knife it should be made sure that it is handled with care as It can lead to severe cuts and cause severe damages.
• While using the acid it should be made sure that it is not spilled over as it cause burns which can be dangerous.

Method:

• You first measure 5 cm3 of hydrochloric acid with the use of a syringe.
• Then you put 5 cm3 of acid in three test tubes.
• After doing this you then measure the dimensions of the agar gel you are using for the experiment.
• Therefore, after this you drop each piece of agar gel in each test tube or beaker and start the stopwatch to measure the time taken for the pink colour to disappear.
• Therefore after taking the time you rinse the test tube well with water and throw away the used acid, throwing the agar gel away.

Results:

Formulas used

Surface area= 2(hl + lb + bh)

Volume= l x b x h

Graphs:

Analysis and error analysis:

From the above results we can see as the Volume: surface area ratio increases the volume and the surface area individually decreases. More the surface area faster the rate of diffusion, but as we see the surface area decreases as the speed of the rate of reaction increases; this is because, the Volume: surface area is different in the ratio as the volume is also less the Volume: surface area ratio increases. Even if the volume is the same the surface area plays an important role in determining the speed of diffusion. The time taken for each ratio forms a linear graph which tells us that the time taken is in proportion.

Error analysis:

As we can see from the graphs, the graph should have been almost a straight line, but this is only witnessed in graph 1, whereas in graph 2 and 3 there are some anomalous results. These are some errors that could have taken place and are as follows:

• While putting the acid from the syringe, in the beaker some of the acid could have stuck to the syringe leading to inaccuracies.

• Since the beaker was reused for all the steps it may have not given accurate results as some of the water after being rinsed could have been left over reducing the concentration of the acid.
• The graph paper was not always accurately visible and therefore this could results in inaccurate results.
• It is possible that the stopwatch was not started exactly when the reaction started. Therefore this could have lead to inaccuracies in the experiment.
• Sometimes the agar gel lid was not always put and this could have resulted in the agar gel going bad and therefore could have led to inaccurate results.
• Sometimes it was not clear as to whether the pink colour had disappeared which is an important factor for an error in the experiment.
• The apparatus was not in best use which could result in many errors.
• There could have been human errors like:

• The stopwatch could have not been stopped at the right time of colour change.
• The syringe reading could have been taken incorrectly by reading from eye level.
• The agar gel piece could have broken inside the test tube increasing the surface area leading to inaccuracies.

Improvements:

There were many errors but these errors could have been corrected and the experiment can be improved by:

• More trials could have been taken so that the results would be more accurate and we would also obtain more variety.
• We could have used more different kinds of ratios, and then also we would get more varied results.
• We should have made sure that the apparatus was in best use so that the inaccuracies would be minimal.
• I should have used more beakers simultaneously so that the experiment would be done faster and the results would also be more accurate.
• I should have used another person in the experiment that could have helped me in the experiment to avoid parallax errors.
• It should have been made sure that the unused agar gel is covered with a lid so that the inaccuracies would also become minimal.
• It should have also been made sure that the same apparatus was used and also the same agar gel dish so that the inaccuracies would be constant for all the trials.

Conclusion:

From the above results, we can conclude that As the Volume: surface area ratio increases the time taken for the reaction decreases. This is because more surface area is exposed and diffusion takes place.