Carry out an experiment investigating the effect of varying acid concentration on the rate of decomposition of limestone on the exterior of the Lincoln Cathedral.

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Lincoln Cathedral Investigation

Planning:

Aim of Investigation:

To carry out an experiment investigating the effect of varying acid concentration on the rate of decomposition of limestone on the exterior of the Lincoln Cathedral.

Preliminary Work:

Aim: To find the most effective acid on the decomposition of limestone.

Equipment: Conical flask

Delivery tube

Water bath

Measuring cylinder

Water

Hydrochloric acid (50cm3)

Nitric acid (50cm3)

Sulphuric acid (50cm3)

Limestone (3 medium sized marble chips)

Stopwatch

Diagram:

Procedure:

Medium marble chip of limestone was added to the conical flask and the inverted measuring cylinder was filled with water. It was carefully tipped into the water bath using the 'up and over' method. 50cm3 of 2M hydrochloric acid was added to the conical flask with the limestone. The delivery tube was put under the measuring cylinder and the timer was started to measure the time taken to collect 50cm3 of carbon dioxide gas.

This procedure was repeated using two other acids; sulphuric and nitric. The acid that produced the fixed amount of carbon dioxide was the most effective acid on the decomposition of limestone and therefore was to be used again in the main investigation.

Results:

Acid

Time taken to produce 50cm3 of CO2 (seconds)

Hydrochloric 2M

317

Sulphuric 2M

No reaction

Nitric 2M

474

Conclusion:

Using the results obtained from the above table, it can be deduced that hydrochloric acid has the greatest effect on the decomposition of limestone. This is because it took the shortest time to produce 50cm3 of carbon dioxide. Therefore hydrochloric acid shall be used in the main investigation.

Variables:
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Variable factor

Vary

Control

Mass of limestone

No

Yes

Temperature

No

Yes

Amount of acid

No

Yes

Concentration of acid

Yes

No

The table above shows that the concentration of acid will be an independent variable and all other factors will be controlled i.e., mass of limestone, temperature and the amount of acid.

Method:

Equipment: Conical flask

Delivery tube

Water bath

Measuring cylinder

Water

Hydrochloric acid (450cm3)

Limestone (15 medium ...

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