Aim:
I have been asked to find out if any of the suppliers have been watering down the vinegar they have supplied to the chip shop owner. I will do this by using a technique called Titration. Vinegar is ethonoic acid
Variables:
- Amount of acid (vinegar)
- Sample of Vinegar
- Type of alkali
- Type of indicator
I will be keeping all the variables the same.
Apparatus:
An Acid
An Alkali
A Burette
A conical flask
A stand and a clamp
A beaker
A Pipette
An Indicator
Prediction:
The acid with the lowest molarity has been watered down.
Method:
Step 1: Wash out all equipment.
Step 2: Set up the equipment.
Step 3: Take out the burette and fill with sodium carbonate.
Step 4: Measure the first acid in the pipette.
Step 5: Dilute the acid with pure H2O so there is a higher volume to work with, then add a few drops of the indicator.
Step 6: Start the titration. When the indicator has changed colour stop immediately.
Step 7: Record results in a table.
Step 8: Repeat all steps with the other acids.
Conclusion:
The acid with the lowest molarity has been watered down. I know this because it took less alkali to neutralise it. Shop B, Safe Way and Shop C have obviously been watered down because they have a lower molarity than shop A. So the chip shop owner should only buy shop A vinegar as it is the strongest and he is getting more vinegar for his money. However shop A could also be watering down their vinegar just not as much as the other shops, unless the chip shop owner gave me a sample of vinegar from the manufacture I could not tell if shop A has been watered down.
Evaluation:
The experiment worked but it did not tell us that the strongest vinegar (shop A) hadn’t been diluted as well as the others.
To ensure my experiment was a fair test I had to make sure all the variables were the same. I made sure the factors which needed to be constant were constant, for example the volume of vinegar was measured accurately; the same amount of indicator was added and the volume of sodium carbonate was measured accurately. This made sure that my results were reliable even though I got one anomalous result.