Chemistry Coursework - Marble and Acid Experiment

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Chemistry Coursework

Marble and Acid Experiment

Aim:

To investigate one factor that effects the rate of reaction between marble chips (calcium carbonate) and dilute hydrochloric acid.

Marble Chips (calcium carbonate) + Hydrochloric Acid

Calcium Chloride + Water + Carbon Dioxide

CaCO3 + 2HCl

CaCl2 + H2O + CO2

Variables:

To alter the rate of reaction between Marble chips and hydrochloric acid, there are a few alterations that could be made.

> Pressure- The greater the pressure of a gas the faster a reaction will occur. This is due the fact that there area greater number of particles in a given volume to react.

> Temperature- if the temperature was raised the experiment would react faster as the particles would be moving faster with more energy.

> Concentration- the concentration of the hydrochloric acid could be lowered by adding different amounts of water. This would slow down the reaction because there are fewer particles in a given volume to react.

> Catalyst- these change the rate by providing an alternative reaction pathway along which the reaction can occur.

> Surface Area- the surface area of the marble chips can be altered by changing their size. Smaller chips of the same mass will have a larger surface area. A larger surface area speeds up the reaction process, as there is a larger surface area to react at any one time.

Altering the pressure is simply not possible, as we do not posses the equipment to do this. Changing the temperature of the experiment is not a good variable as in the classroom environment; it is very hard to make the experiment a fair test with the equipment available to us. Catalysts are not available for use in this experiment. It is possible to alter the surface area of the chips but the problem lies in the fact that all of the chips vary in size and so you could never measure the differences in surface areas.

Due to this I have decided to alter the concentration in my experiment. This is not only due to the problems involving other variables but it is also possible to receive clear, accurate results when altering the concentration.
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Fair Test:

To ensure accurate results we must ensure that we have a fair test. This means that each testing must be made to be identical to the last bar the variable we shall be altering. In each experiment, the same amount of Marble Chips (5g) and water to be displaced (100 cm3) must be used.

Also to ensure a fair test, we shall use the same equipment for each test and the experiments will be done in the same room at close intervals to ensure that the temperature for each is as close as possible ...

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