Crumbling CastlesWhat is the Effect of Nitric Acid on Limestone?

• Fair Test: Keep mass of limestone and volume of acid the same.
• Reliable Test: Repeat the test 3 or more times on each ‘stage’.
• Accurate Test: Try to keep the surrounding temperature and all other variables the same.

Equipment List

• Conical Flask

• Gas Syringe
• Scales
• Measuring Cylinder
• Beaker
• Pipette
• Nitric Acid
• Calcium Carbonate (Limestone)

Detailed Plan

• Measure out 20cm2 of 1 molar nitric acid and 1g of limestone.
• Take the 1g of limestone and 20cm2 of 1 molar nitric acid and put them in a conical flask.
• Put the gas syringe on the conical flask immediately.
• Leave for 3 minutes.
• Take out syringe and record the volume of gas produced.
• Repeat test at least 3 times.
• Repeat the test with 20cm2 of, for example, 0.8m, 0.6m, 0.4m, 0.2m and 0.0m, nitric acid.
• To make 20cm2 of 0.6m nitric acid, for example, put 12cm2 of 1m nitric acid in a measuring cylinder with a pipette and 8cm2 of water.
• Record the volumes of gas produced.
• Lay out all results in a table.

Prediction

I predict that the stronger the acid with the limestone the more gas will be produced because if there is more acid molecules in the solution there will be more “stuff” there for the limestone to react with. This will happen until the solution becomes saturated or all of the limestone is used up.

1-Mass of limestone becomes limiting factor

Safety

• Goggles
• Careful Procedure

Results

As I predicted, as the concentration of acid decreases, the volume of gas produced decreases. There is sudden drop from 0.8-0.6 molar acids and all of “Trial 3” is a lot higher than the others, this could have happened because the concentration of the acid was greater.

Evaluation

All the results of “Trial 3” were higher than I had expected. This may have happened because the concentration of acid wasn’t correct and was too strong or the temperature of the room might have been hotter.

I think the results are reliable because I took them 3 times and trials 1 + 2 are roughly the same.

To improve the experiment I would do it all on the same day because the temperature of the room may have altered on the different days. This would affect the experiment because the hotter the solution is the more reacting there would be.