Rates of Reaction: Hydrochloric Acid + Calcium Carbonate

Background Information: Hydrochloric acid is a clear, colourless, highly-pungent solution of hydrogen chloride (HCl) in water. It is a highly corrosive, strong mineral acid with many industrial uses. Hydrochloric acid is found naturally in gastric acid. Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. When these two reactants are combined results in the production of Calcium Chloride (CaC2), Carbon Dioxide (Co2) and Water (H2O).

Aim: To investigate the rate of reaction between Calcium Carbonate (CaCo3) and hydrochloric acid (HCl) by changing the molarity of the acid and measuring how much Carbon Dioxide (Co2) is produced. Hypothesis: I predict that the higher the molar concentration of the acid the faster the reaction will take place therefor creating more gas in a shorter amount of time. I think this will happen because when the acidity is higher the solution is stronger which then speeds up the reaction process. Safety: For safety I will wear safety goggles to protect my eyes from the possibility of the acid splashing on my face. I will also wear a protective lab coat to stop the acid splashing and burning my clothes and skin.

Apparatus:

· Conical Flask

· Measuring cylinders (15ml, 25 ml, 50ml, 100ml)

· 45 ml of hydrochloric acid (0.5 m, 1 m, 1.5 m, 2 m, 2.5 m)

· 5.4g of calcium carbonate (chip)
– Stand
– Clamp
-Boss head

· Timer.

· Bung. (rubber stopper)
-Electronic scales
-Tea Strainer
Method:
· I will measure out 10 ml of Hydrochloric Acid and pour this into a small beaker. (First 0.1 molar) repeat 3 times for each concentration.

· I will set up the clamp, stand and measuring cylinder.

· I will weigh 0.3 grams of Calcium Carbonate chips on pieces of filter paper. Repeat 15 times.

· I will drop the Calcium Carbonate into conical flask.

· I will pour the Hydrochloric acid in and quickly fasten the bung. At the same time another person will start the timer.

· I will note down in my table how much gas is in the measuring cylinder every for each test. Repeat three times for each concentration of acid

· I will use the same method with the hydrochloric acid 0.1 molar, 0.5 molar, 1.0 molar, 1.5 molar, 2.0 molar. -Once you have finished testing each concentration, pour the solution through the tea strainer and tap away the Calium on a paper towel. Accuracy: To make my experiment accurate I am repeating the experiment three times, I am measuring the gas carefully throughout the experiment and I am measuring the calcium carbonate carefully on highly responsive scales. Finally, I am measuring the amount of hydrochloric acid very carefully and accurately.

Diagram:

Variables:
-Independent: The molarity of the concentration of Hydrochloric Acid -Dependant: The amount of Carbon Dioxide (Co2) produced per 30 seconds Co2/30s -Controls: Temperature of Hydrochloric Acid, the timing, the amount of Calcium Carbonate chips, gas measurement.

Discussion: As shown in the graph and table above, each test had a very similar result to the other tests of the same concentration. The most they differed by was 1.5 ml of water displaced. As for the difference between concentrations, there is definitely a strong affect as the lowest concentration averages 7.5ml displaced per 30 seconds whereas the highest concentration averaged 21.5 ml displaced per 30 seconds, almost triple the lowest. Also concentrations from 0.5m – 2.0 m are each about 3 ml differences whereas the difference between 0.1 m and 0.5 m is almost 5ml. This shows how weak the 0.1 m concentration is and if you compared that to a much higher concentration there would be a very large difference. This also makes the 0.1 a minor outlier or anomalous data as it further out of the range and doesn’t exactly follow the trend or pattern like the others do.

Evaluation: Overall I think that my experiment was a success, form the performance to the results. During the execution of my practical I was very accurate with my measurements and tidy with my work space. If I was to compare this practical with my last experiment on gelatin I would be majorly impressed. Not only was it a more advanced and more calculated experiment it, the results reflect what I was trying to find out in a clear and exact manor. Also I made absolutely sure that I was as accurate as I possibly could be. I used the scales and measured the Calcium Carbonate to the exact same 0.3 grams every time, I fastened the bung as quickly as I possibly could once the acid had been added and I wrote down my results right on 30 seconds. I am very happy with how everything turned out with this experiment and I am sure that the results that I have gathered are accurate.

Conclusion: In conclusion, absolutely everything went to plan and not much at all could have been improved. In fact, the only thing that could have been improved would be how quickly I fastened the bung and started the timer but this was very hard there was a lot to do in that very short time span. Also I think that my results are shown clearly in the graph and table above and reflect the success of my experiment. If I was to test this experiment again, the only thing that I would change would be to use higher concentrations of Hydrochloric Acid. This is because I think the more obvious reaction would have been clearer and would demonstrate the patterns and trends of the data more effectively. My hypothesis was correct, as the concentration gets higher the reaction creates more Carbon Dioxide per
period of time.