There are a few methods that could be used to carry out this experiment. The rate of reaction could be measured using the following methods:
- Measuring the loss of gas using the gas syringe method
- Measuring the time taken for the Calcium Carbonate to dissolve.
- Measuring the amount of mass being released using a top pan balance.
Measuring the loss of gas could be measured by using the gas syringe method. This experiment would be done by placing the rubber bung on top of the conical flask. The rate of reaction could be measured by calculating the amount of gas being released in a certain amount of time such as at every 30 seconds. It could be measured by calculating the amount of gas being released until the end of the experiment or measuring the volume of gas being released throughout the experiment and this would be done in intervals.
Measuring how long it takes for Calcium Carbonate to dissolve in different concentrations of Hydrochloric acid and water. This would be done by using a conical flask. The different concentrations of Hydrochloric acid and water would be placed in the conical flack followed by an amount of Calcium Carbonate. When the Calcium Carbonate is placed into the conical flask the timing would begin and stop when no more Calcium Carbonate is visible and this would give the speed of how long it takes for the reaction to have been complete.
Measuring the amount of mass loss would be measured by using a top pan balance. We would put the Calcium Carbonate powder into hydrochloric acid and water. We could then time how long it takes for a reaction to take place by measuring the amount of gas being lost in a certain amount of time or how much mass has been lost until the end of the experiment.
Our group decided to time how long it takes for Calcium Carbonate to dissolve using different concentrations of diluted Hydrochloric acid and water. All the diluted concentration would be at the same volume. We will also try to use the gas syringe method as back up/preliminary results. Before doing the experiment we had a practice run through. We used our results and other information to come up with a decision of what method to use. In the practice experiment we got into two groups and did two different experiments to get double the results. During the run through we found that timing the speed of reaction of how long it takes for Calcium Carbonate to dissolve was the easiest. These results were more accurate than the gas syringe method. Measuring the gas being released took long to get results and when we did, they weren’t accurate or as we expected. Using the results and information we decided to time how long it took for Calcium Carbonate do dissolve in diluted Hydrochloric acid and water. We experimented with different concentrations of Calcium Carbonate and Hydrochloric acid.
Using the run through experiment we decided as a group to use the following measurements
Using the measurements above we will do experiments 1,2,3,4 and 5, three times. The purpose of doing the experiment three times is so that we can get more results allowing us to get an average. When we get our results we hope to achieve accurate and reliable results. If anything happens to go wrong in the results we will do that particular experiment again and try and find out what caused the results to vary and why.
Apparatus:
-Conical flasks - Pipit
-Gas syringe (rubber tubing) - Measuring cylinders
-Stop clock - Digital measuring scale
-Goggles -Spatula
Solutions used:
Calcium Carbonate
Hydrochloric acid
Below is a picture showing how to set up the experiment where we are trying to find the speed of how long it takes for the Calcium Carbonate powder to dissolve.
Below is a picture showing how to set up the experiment where we are trying to find how much gas is being released in a certain time.
Some of the equipment that we are using is to get our measuring as accurate as possible. We are using the stop clock to get the time/speed as accurate as possible, this is because it is very reliable, as you can start and stop it very quickly, whenever you want. A pipit is very good for fair testing as it can be used to carry very small amounts of Hydrochloric acid into the measuring cylinder. The measuring cylinder is also used for fair testing as it measures all the solution accurately, and a measuring scale is also very accurate as measures the mass pf Calcium Carbonate accurately.
Method:
- Set up the equipment as shown in the diagram in the prediction on the previous page. This is the experiment were we are measuring the time of how long it takes for the Calcium Carbonate to dissolve in different concentrations of Hydrochloric acid.
- The first thing you mush start of with is to put on your goggles. This is for safety. The goggles are to protect your eyes incase some solution splats on you and if this does happen it can be very dangerous.
- Before you start anything you must give everyone a job to do, for example, one person measures the solutions the other measures the powder, someone starts the clock watch, someone pours the Calcium Carbonate, and someone shakes the conical flask. This is to make sure that the experiment is as accurate as possible, and because every one has different reaction speeds and different hand, eye co-ordination it would be fair if one person stuck to doing the same thing throughout the whole of the experiment.
- Plug in the digital scale and measure 2.5grams of Calcium Carbonate powder on a piece of paper.
- Measure 25ml of Hydrochloric acid and put it into the conical flask with 5ml of water.
- Now one person needs to put in the Calcium Carbonate into the conical flask and at the same time the other person must start the stop clock as quick as possible.
- Make sure that one-person stays with the experiment at all times as you will not know how long the experiment will take.
- 30 seconds into the experiment one person should shake the conical flask around, in one direction, 3 times.
- If the conical flask gets cloudy then pick it up and look at the bottom and when the Calcium Carbonate is no longer visible stop the stop clock.
- Record the results in suitable table, like shown below.
- You must now do experiments 2,3,4 and 5 using the different concentrations.
- Now do all the experiments again twice so you have three sets of results. The purpose of this is to get more results that are accurate.
- If your results vary a lot then do the experiment again until you get more accurate readings.
- Now make an average of your results. This is because an average is more reliable tan single results.
- Finally make sure that you have enough results to draw up a conclusion.
We knew that we had enough result to draw a conclusion because we could see a pattern occurring in the results and average.
Preliminary results:
Below is a set of our preliminary results. We used preliminary results so that if the method of measuring the time in how long it took for the Calcium Carbonate to dissolve in different concentrations of Hydrochloric acid didn’t work, we would use these results for secondary results.
In this experiment we measured the gas produced in 30 seconds.
We stopped this experiment because as the concentration of hydrochloric acid decreased the amount of gas produced increased and looking at all the evidence we had we were sure that this should not be happening. We through this was because we were diluting the Hydrochloric acid with water and so we tried using 30cm3 of hydrochloric acid containing different moles in the below table of results.
We found that the reaction was to fast so we tried using 15cm3 of Hydrochloric acid containing different moles and measured the amount of gas let out in 30
seconds. We used 15cm3 because it would be less concentrated as there would be less hydrochloric acid as there was in the above table.
In this experiment we only managed to get 1 result because the other two experiments (with more moles) were to quick and therefore we were unable to record them.
Our results:
After getting only one set of results from all the results I could already see a pattern. Although this happened we continued to get another 2 set of result, this was so that could get more result giving us an average, and it would also be more reliable and accurate.
Our results are shown on the table below.
KEY:
Results 1.
Results 2.
Results 3.
This is bar graph showing the results of each experiment and both repeat experi-ments. The graph shows that as the conc-entration of HCl decreases the time taken for CaCo3 to dissolve increases. It also shows that the repeat results are similar.
We used a range of concentrations varying from 5cm3 to 25cm3 and it gave a clear result.
We decided to change the volume of Hydrochloric acid and water to give the different concentrations, which worked very well.
Here is another graph showing the pattern in the averages of each experiment. The pattern shows the same pattern as the bar graph on the previous page. The pattern is that as the concentration of Hydrochloric acid decreases the rate at which Calcium Carbonate dissolves decreases, and below is another graph showing the pattern in the averages of each experiment.
Line of best fit.
These results are very good as they show a clear indication of what has happened in the experiment, when the concentration of Hydrochloric acid is increased, and therefore, it will help with coming up with a conclusion.
Conclusion:
In conclusion I found that the higher the concentration of Hydrochloric acid the quicker the rate of reaction. This is because there are more partials of Hydrochloric acid for Calcium Carbonate to collide with and therefore the quicker the reaction will take place.
Particles can only react if they collide with enough kinetic energy for the reaction to talk place. This theory is called the collision theory. There are four factors that can change the rate of a chemical reaction; they are temperature, concentration, surface area and the use of a suitable catalyst.
The temperature gives more energy, concentration means more particles, surface area gives a greater area for the reactant to be exposed and so available for a collision and using a suitable catalyst means particles having only moderate energy may react.
My prediction and the results are very similar s I believed that there would be a quicker reaction with a higher concentration of Hydrochloric acid. I believed this because more particles would collide with a higher concentration and so a quicker reaction would take place.
