Investigating the rate of a reaction, between calcium carbonate and hydrochloric acid.

Authors Avatar

Chemistry Coursework                                                                             Lee Battu 11H

Investigating Reaction Rates

Aim:

I am investigating the rate of a reaction, which is between calcium carbonate and hydrochloric acid, and to do this I have chosen the concentration of the acid as my variable for the experiment. The products of a reaction between calcium carbonate and hydrochloric acid is calcium chloride, carbon dioxide and water.

CaCo3 + 2HCL = CaCL2 + H2O + CO2

So to measure the rate of reaction I will be measuring the time it takes to produce a certain amount of carbon dioxide. But to make the experiment fair I have to fix all of the other variables that affect my results.

Variables

Surface area of solid - The surface area has an effect on the rate of reaction as the larger the surface area of a solid the more opportunities there are for collisions to occur with the liquid. If the surface area is small, collisions can only occur with the outer atoms and is therefore limited. This variable however is difficult to weigh and measure thus I am not choosing to use it. There are three different sizes of marble chips available for me to use and to keep this variable fixed I must only use the same one throughout the experiment.

The temperature of the reaction - When the temperature is low, the particles in the reaction do not have much energy so collision is unlikely to occur. However on heating, particles increase their kinetic energy thus causing them to move faster and collide more often. Because the collisions have more energy they are more likely to be successful in breaking and reforming bonds. Therefore the rate of the reaction will increase. But I am not using this variable for my experiment and so it needs to be fixed and I will use room temperature to do this.

Presence of a catalyst - A catalyst increases the rate of a chemical reaction without itself being used up. Catalysts are usually transition metals. In the presence of a catalyst, less energy is needed by a collision in order to be successful as the activation energy is lowered. Therefore there are relatively more successful collisions and so the reaction rate increases. However, a catalyst will not be used in this reaction.

Amount of the reactants – This will obviously have an effect on the results if not controlled because if you increase the number of particles, you increase the number of collisions and so the rate increases. Fixed values will have to be decided to stop this from occurring.

Join now!

Preliminary Experiment

I have chosen to investigate how concentration affects the rate of reaction. I was initially going to grind up 10grams of marble chips, but soon realised that this measurement was much to big, and reduced it to 1gram of powder. However, this lead to discrepancies considering droplets of water in our test tube would mix with the calcium carbonate when it was tipped in. So the test tube had wet powder all up along the sides of the test tube, and it could therefore not mix with the hydrochloric acid being poured in. Also the calcium carbonate powder ...

This is a preview of the whole essay