Calcium Carbonate and Hydrochloric Acid

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Calcium Carbonate and Hydrochloric Acid

Surface area affecting the reaction rate


In this experiment calsium carbonate (CaCO3) will be put into a flask and then mixed with Hydrochloric Acid (HCl).

The reaction is:
3(s) + 2HCl(l) --> CaCl2(aq) + H2O(l) + CO2(g)

The purpose of the experiment is to determine whether or not increasing surface area of marble chips will increase the reaction rate.

Reaction rate is a way of measuring how fast the reaction takes place. So the higher the reaction rate the faster the reaction takes place and the lower is the reaction time is.

Research Question

How does reaction rate change with increasing surface area of calcium carbonate in hydrochloric acid ?


With increasing surface area of marble chips the reaction rate will also increase.


For the same mass of the calcium carbonate, powder has a larger surface area than marble chips. As the

collision theory states for a chemical reaction to occur particles need to collide at a certain speed and

angle. With increasing surface area, more surface area is available for the collisions to occur on. So when the surface area increases more collisions happen and therefore the reaction rate increases.


  • Hydrochloric acid HCl(l),
  • Calcium carbonate (marble chips) CaCO3(g)
  • Calcium carbonate (powder) CaCO3(g)
  • 250 ml3 flask
  • 50 ml3 measuring cylinder
  • Electronic scale
  • Stop clock
  • Cotton


Reaction time is the dependent variable, as it depends on the surface area of the marble chips.

The surface area of calcium carbonate is the independent variable, as it does not depend in anything. This can also be concluded from the fact that it is the surface area that is changed in this experiment.

The concentration and the amount of the acid used are the controlled variables, as they have to stay constant throughout the experiment

Method of data collection

It is important to carry out this experiment in a safe way, due to the fact that hydrochloric acid is being used. Hydrochloric acid is highly dangerous as it can damage skin and eyes. To carry out the investigation in a safe way goggles and an apron were on all the time. The area where the experiment took place was cleaned before the experiment. The desk was whipped and any obstacles that could affect the experiment from being carried out without any disruptions.

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  1. Preparations for the reaction
  • Measured 50 ml3 (± 1,0 ml3) HCl in the 50 ml3 measuring cylinder
  • Weighed 1,0 g (± 0,0001g) of marble chips on the electronic scale (which accounted 4 decimals)
  • The flask with cotton on top was placed on the scale and the scale was adjusted to 0,0000 g
  • The calcium carbonate (marble chips) was put into the flask
  • The stop clock and cotton were placed next to the digital scale so they are ready for use

Now the reaction was ready to take place.

  1. HCl was poured into the ...

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