Hydrochloric Acid+Calcium Carbonate Investigation

Activation energy - The amount of energy needed for the reaction to be started. If there is enough energy then the reaction takes place and a product is formed, but if there isn't enough then no reaction takes place.

Prediction

The more concentrated the acid then the quicker the reaction will take place, because there will be more Hydrochloric Acid ions than water molecules for the marble chips to collide with and therefore react. More collisions between the two reactants will take place resulting in a quicker time for the reaction.

I predict that if the concentration of the Hydrochloric Acid is doubled then the experiment will happen twice as fast. This is because twice as many Hydrochloric Acid ions will be present than previously and there will be twice as much chance of the calcium carbonate chips colliding with the concentrated hydrochloric acid. Therefore when the concentration is double the time take for the reaction should be halved.

Apparatus

The solutions with different concentrations of acid have to be prepared before the reactions can start. The solution has to have a total volume of 20ml. The following solutions should be prepared by mixing water and the acid in a set ratio.

When the solutions have been prepared the apparatus has to be set up. The following equipment will be needed for the experiment.

Method

. Put goggles on.

2. Fill water tub with water and stand one measuring cylinder full of water upside down in the tub.

3. Place the unbunged end of delivery tube in the bottom of the upside down measuring cylinder.

4. Pour 20ml of acid solution into a conical flask.

5. Place 5g of Calcium Carbonate into the conical flask with the acid in, put the bunged end of the delivery tube into the neck of the delivery tube and start the stop clock.

6. Once 30cm³ of Carbon Dioxide has collected, stop the stop clock and record the result.

7. Repeat steps 2-6 for each variable 3 times

Results

Rate Of Reaction

Conclusion

I found that as I increased the concentration of the acid, there was a faster reaction. Hence more Carbon Dioxide gas produced. By looking at graph, line for the least concentrated solution was the least steep and this meant it was also the slowest.

The experiment was a success. When I done this experiment I found that concentration is a factor that affects the rate of reaction, and proved my prediction right.

When explaining why the rate of reaction quicker the collision theory explains why. When the concentration of acid is higher, there are a higher number of the ions to collide with the Calcium Carbonate molecules that then results in a reaction. The more collisions, the quicker the reaction. In this reaction the following substances react and are produced:

Reactants: Hydrochloric Acid (HCl) and Calcium Carbonate (CaCO3)

Products: Calcium Chloride (CaCl), Carbon Dioxide (CO2) and Water (H2O)

This gives us the following formula:

2HCl + CaCO3 -----> CaCl2 + CO2 + H2O

By looking at the formula we can already see that there is equal numbers of particles in both the Acid ion and the Calcium Carbonate molecule. By reducing the concentration of the acid the ration will be reduced, thus leading to slower reaction times.

Evaluation

I think the results I collected are sufficient to support a firm conclusion but the reliability of a small amount of the data was in doubt. As you can see in the table of results, in the average column there is one result out of place, 60%.

To improve the accuracy of the experiments I would have the Calcium Carbonate chips weighed out more precisely, the acid concentrations mixed more accurately and the timing done more accurately. Theses few changes I feel will make the whole investigation more thorough and help to prove my prediction greater.