Investigating the Effect of Concentration on the Rate of Diffusion
Aim: To find out if concentration affects the rate of diffusion.
Prediction: I predict that the higher the concentration of acid the faster the reaction will be.
Hypothesis: Diffusion is the spreading out of a gas or liquid from an area of low concentration to another area where it has a lower concentration until the overall concentrations are balanced. The
Hydrochloric acid (HCl) diffuses into the gelatine cube of which contains Sodium Hydroxide (NaOH), which is an alkali. When the
Hydrochloric acid combines with the Sodium Hydroxide they form salt and water, which is neutral therefore turning the pink cube to clear.
Dependent variable: We are measuring the time taken for the pink indicator to turn clear when hydrochloric acid is added to it.
Independent variable: We are changing the molar of hydrochloric acid we are adding to the gelatine cubes. The molars range from 1-3.
Apparatus:
* 1 measuring cylinder
* 1 test tube
* 1 stop clock
* A large gelatine cube containing indicator and NaOH
* Hydrochloric acid ranging from 1-3 molars
* A scalpel
Diagram:
Method:
* Take the large gelatine cube and cut into 15 equal pieces
* Place on piece of the cube into the test tube
* Measure out 10mls of HCl in the measuring cylinder
* Pour the HCl into the test tube with the gelatine cube and start the clock
* Time how long it takes for the pink colour inside the gelatine cube to completely disappear
* You will also notice that the cube dissolves slightly
* Record your results and repeat this same process 3 times for each molar of acid:
§ 1 molar
§ 1.5 molar
§ 2 molar
§ 2.5 molar
§ 3 molar
Fair test: To ensure that this experiment is a fair test I will take a number of precautions:
* Ensure that all the gelatine cubes are the same size so that the time taken for is accurate
* Ensure that the acid is measured out to exactly 10mls each time to keep it fair
* Use the same equipment each time so there are no variations
Safety: To make sure that this experiment is safe you should wear safety goggles so as not get and HCl into your eyes at it is highly corrosive and irritant. You should also tuck your tie into your shirt so that it does not hang into the HCl or any other part of the equipment or apparatus. Make sure you have a clear working area so that no accidents occur whilst you are conducting your investigation.
There is no Bunsen burner or any other dangerous equipment in involved in this investigation apart form the HCl therefore there are not many safety precautions.
Results Table:
Molar of HCl
------------
1 (mins)
2(mins)
3(mins)
Average:
3
10.04
10.17
9.36
9.86
2.5
10.28
10.29
10.30
10.29
2
10.20
9.22
9.50
9.64
1.5
7.29
7.15
5.59
6.68
1
5.39
6.27
5.43
5.70
Conclusion: As you can see my results are very different to what I
have
