What factors affect the rate of decay of a limestone castle?

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What factors affect the rate of decay of a limestone castle?

A local town has a castle. The castle is built from Limestone (Calcium Carbonate). The castle has started to crumble. Some people have blamed the new damage on acid rain and have stated that the damage has increased as pollution has increased. Others blame Global warming and claim that the level of acid in the rain has stayed the same.

Choose ONE factor to investigate to find the reason for the decay of the castle.

The reaction is:

Calcium Carbonate  +  Nitric Acid  -------->  Calcium Nitrate                                                                          +  Water  +                                                                  Carbon Dioxide

Intro

  • I decided to investigate the affect that acid rain would have on the limestone, which the castle is built of.
  • For this, I decided to do an experiment involving immersing limestone chips in different concentrations of acid.

Hypothesis

I think that the acid will dissolve the marble chips in the experiment that I am about to perform. As I change the independant variable, the rate at which the marble chips dissolve and how much they do in the given time will vary. I think that if the acid concentration is high, then the marble chips will dissolve faster. If the concentration of acid is low or if acid is not present, the marble chips will dissolve slowly. I also think that the reaction between the calcium carbonate (marble chips) and the nitric acid will omit carbon dioxide, as shown in the equation above. This will become apparent whilst doing the experiment. I think that we will be able to see how much carbon dioxide is let off in each component of the experiment, due to how each one reacts.

Apparatus

Marble chips

1 Molar of Nitric Acid

Conical flask

Water trough

100cm3 measuring cylinder

Stopwatch

Beehive jar

Gas jar

Thistle funnel

Water

Glass slide

Step-by-Step Plan

  • My independent variable in these experiments will be the acid and its concentration, which I will vary using larger or smaller amounts of acid diluted with water for each component.
  • The weight of the marble chips will remain the same.
  • The volume of the water will remain the same.
  • The marble chips and the acid will be put in a conical flask. This will have a bung in the top, with a thistle funnel inserted so that it will dip in the acid and water solution.
  • The thistle funnel will have a cotton wool bud inserted, so that the water and/or acid will be prevented from bubbling up the tube.
  • The conical flask will have a tube inserted in it, which will lead to the underneath of the beehive. This is the tube, which the gas will travel down.
  • On the top of the beehive jar, where a hole is, is where the gas jar will stand. The gas jar will be filled with water.
  • The beehive and the gas jar will stand in a trough filled with water.
  • The amount by which the water disappears in the gas jar and goes down due to the gas carbon dioxide transferring to the jar will be monitored in each component of the experiments 1, 2 and 3.
  • Throughout the experiments that I am doing, I will be wearing safety goggles to prevent any acid getting in contact with my eyes. Also, an overall will be worn to protect against any spillages.
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Variables

For my experiments, I will have to keep some elements the same in order to make this a fair test. The weight of the marble chips will remain at 90 grams for each component of my experiments. The volume of acid and/or water will total at 40cm3 for each component of my experiments. The reaction of the marble chips in the acid will be timed for 2 minutes in each component of the experiments. The set up of the apparatus will be exactly the same for each component with no variations. I will follow these guidelines strictly ...

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