Aim
In this experiment we will be trying to find out how the concentration of hydrochloric acid affects its rate of reactant with calcium carbonate.
The equation for this reaction is:
Calcium Carbonate + Hydrochloric Acid → Calcium Chloride + Water + Carbon Dioxide
CaCO + 2HCL →CaCL + H O + CO
Equipment List
- Calcium Carbonate Powder
- Dilute Hydrochloric Acid
- Conical Flask
- Rubber Bung
- Beehive Shelf
- Measuring Cylinder
- Stop Clock
- Container
- Delivery Tube
- Water
Safety
To make sure this experiment Is safe …
- Tie long hair back
- Wear safety goggles
- Stand up whilst doing the experiment
- Tuck in stools
- Tuck bags under table
- Do not run
- Clear the table before doing the experiment
- Inform teacher in case of spillage
- Wash hands when finished
- Do not put chemicals near face
- Do not eat whilst doing the experiment
- Clear away equipment after experiment
- Acid must be kept off skin, clothes, work surfaces and treated carefully as it is corrosive.
Diagram
Method
- Collect all equipment needed.
- Set up equipment as shown in diagram.
- Fill the container with water from the tap and place the beehive shelf in the centre of the container.
- Put 50 cm3 of dilute hydrochloric acid and 10 g of calcium carbonate powder into the conical flask.
- Put the rubber bung in the top of the flask to seal it.
- Fill the measuring cylinder with water and turn it upside down on top of the beehive shelf.
- Connect the delivery tube from the flask to the beehive shelf.
- Use a stop clock to time the experiment.
- Record your results in your results table.
- Repeat trial with each different concentration of acid
- Complete two series of trials
Fair Test
In order to make this experiment a fair test I will change one variable and keep the others the same throughout. The variable I will change is the concentration (molarity) of the acid. I will keep the following variables the same:
- The amount of Calcium Carbonate Powder must stay the same because if there is more powder, it is likely to speed up the rate of reaction because there will be more particles to react.
- The amount of Dilute Hydrochloric Acid must stay the same for the same reason
- The temperature of water used must stay the same because if the water is hotter it will make the gas expand causing the measurement of the volume of gas produced to change.
- The size of delivery tube must stay the same so that the gas produced can always get through at the same rate
- The stop clock should start at 0.00 each time so we can measure the time accurately.
- The amount of movement should be the same each time because moving it will give the particles more energy speeding up the rate of reaction.
- You must make sure the flask is cleaned and dried between trials so there is no substance left from the last experiment to affect the concentration.
Taking Measurements/Accuracy
During each trial I will a take reading of how much carbon dioxide is given off. I will take this reading after 30 seconds timed by the stop clock and I will make each trial with a different concentration of acid each time. The concentration of the acid will start at 0.2 moles and rise by 0.2 moles each time until the final solution, which will be 1 mole.
I will do this experiment twice so I can make sure I get an accurate reading of the amount carbon dioxide produced. If I do it twice then there will be less chance of the result being affected by anomalies.
Prediction
Using the collision theory I predict that the higher the concentration of acid the more carbon dioxide will be produced.
I predict this because all substances are made up of particles and in order for a chemical reaction to take place all the particles need to collide.
The more particles that collide, the faster the chemical reaction. By using this theory I can predict that the more concentrated the acid, the quicker the reaction takes place. This is because there are more acid particles in a more concentrated solution. The dilute hydrochloric acid can only react with the calcium carbonate when they collide with sufficient activation energy.
Results
Analysis of Results
On finding the results of this experiment I can state that my prediction was correct.
The higher the concentration of acid, the more carbon dioxide was produced in the 30 seconds.
I can tell this by my results graph. It clearly shows the increase of carbon dioxide produced as the concentration of acid increases. There was a sharp increase in the amount of carbon dioxide produced when the concentration of the acid increases from 0.2m to 0.4m, it almost triples in amount. Between 0.4m and 1m, the amount of carbon dioxide produced almost doubles.
The results of the two trials I did were very similar except for the trials with the acid at 0.8m. There was a difference of 20cm3 between the two trials, which is roughly a 10% difference. This might have been caused by:
- Different room temperatures
- Causing movement when you put in the Calcium Carbonate powder
- Inaccuracy in timing
- Inaccuracy in measuring the amount of acid
- Inaccuracy in measuring the amount of Calcium Carbonate
Overall Evaluation
Although the experiment agreed with my prediction there are a lot of variables that were not controlled very well.
- I did not ensure that the experiment was done in an environment at a constant temperature. As I did it over a number of days the room temperature may have varied and affected the results. I could improve this by controlling the temperature more carefully.
- The size of the particles of calcium carbonate may not have been consistent. I could improve this by sieving it to make sure I used particles of more closely the same size.
Overall I think the experiment generally went well as the results seemed to agree with theory and my prediction. However, this is a very small sample of trials and for the results to be more reliable you would have to carry out more trials.
