Safety
While carrying out this experiment I will make sure that I wear goggles throughout the experiment as I will be using and handling acid. During the experiment we shall be wearing labcoats so that the acid does not come in contact with our clothing or any other parts of our body. If the acid does happen to be in contact with my or anyone else’s skin, then it should immediately be washed off with cold water. Medical advice should then be followed. If the acid comes in contact with the eye then the eyewash should be used which is situated at the front of the laboratory.
The environment in which the experiment takes place should also be safe. Items such as coats, bags, stationary etc should be away from the workbench. After the experiment has been completed, the benches should be wiped in case any acid is on the surface. All the apparatus should be placed in their regular place to avoid confusion.
Fair Test
I shall try to keep the following things the same:
- Acid- Hydrochloric acid
- Volume of acid- 100ml
- Same concentration of acid- 2mol
- Type of Carbonate- Calcium Carbonate
- Same scales- to keep the measurements as accurate as possible.
- Same room
- Temperature- room temperature
These are the main features for the experiment to be the same. I shall try my hardest to keep these factors the same so that the results are fair, accurate and reliable as possible. We cannot keep the temperature exactly the same each time but if there is only a small difference it shouldn’t really affect the experiment.
Prediction
I predict that if you double the mass of the carbonate then the amount of gas given off will also double. I will also expect to have graph with a straight line going through the origin. The graph that I should have is shown below:
There are two forms of Calcium Carbonate that we could use. There was powder and chips. In my preliminary work I used both and found out that
the chips took a longer time to react. This is because it will take longer for the chips to react fully with the acid as very little surface area is actually exposed. The acid can only react with that small part resulting in collisions to be limited. If powder is used rather than chips then the surface area would have increased by a great deal. There will be more Calcium Carbonate in contact with the acid resulting in more collisions to be taking place. Due to this fact I shall use the powder form of calcium carbonate.
Below are some calculations to show the amount of gas given off from each mass:
CaCo + HCL CaCl + Co + H O
1 mole 1 mole
100g 24,000 cm³
1g 24000 ÷ 100 = 240 cm³
0.1g 240 ÷ 10 = 24 cm³
0.2g 24 x 2 = 48cm³
0.3g 24 x 3 = 72cm³
0.4g 24 x 4 = 96cm³
0.5g 24 x 5 = 120cm³
0.6g 24 x 6 = 144cm³
0.7g 24 x 7 = 168cm³
0.8g 24 x 8 = 192cm³
0.9g 24 x 9 = 216cm³
1.0g 240cm³
As we can see from the information above if you double the mass, the amount of gas given off also doubles. For example:
0.5g of Calcium Carbonate gives 120cm³of gas
1.0g of Calcium Carbonate gives 240cm³of gas
Apparatus
Below is a list of the equipment that I need to use for the experiment:
- Beaker
- Measuring Cylinder
- Clamp and boss
- Stand
- Water bath
- Calcium Carbonate - powder
- Hydrochloric acid
- Goggles
- Lab coat
- Electronic scales
- Bung
- Water
- Flat bottomed flask
- Delivery tube with attached bung
- Ignition tube
- Stopwatch
- Spatula
Diagram
Method
Below is a copy of my method. I have made it as clear as possible and tried to use the most effective ways in which to obtain the best results.
- Collect all the apparatus mentioned on the page before.
- Set up the equipment as shown above.
- Weigh the amount of Calcium Carbonate powder needed on the scales
- Put the carbonate in an ignition tube
- Collect 100ml of Hydrochloric acid.
- Pour the acid into the flat bottomed flask
- Measure the amount of water in the test tube
- Tilt the flat bottomed flask to an angle of about 45°. Then put the mini tube on the edge of the flat bottomed flask so that it is still at the neck of the flask.
- Hold the bung in one hand and the flask in the other. Then put the bung on the flask and put it straight on the bench so that the mini tube goes to the bottom of the flask.
- Shake the flask for 10 seconds using the stopwatch.
- Wait for the experiment to finish. You will know this will happen when there are no more bubbles going up the measuring cylinder.
- Record the result.
- Clean the apparatus with water
- Collect a new mass and acid. Only do this if you have repeated the mass three times.
- Start the experiment all over again.
REPEAT EACH EXPERIMENT THREE TIMES AND THEN WORK OUT AN AVERAGE.
Preliminary work
I did some preliminary work to try and see if my method worked correctly and also to improve my method.
The results that I obtained are shown in the table below:
Blue This represents the results that were with the powdered form of Calcium Carbonate.
blue This represents the results that were within 10% of what they should be.
I was pleased that 3 of my results were within 10% of what they should be. This proves that my method worked successful on some results. The results are not exactly what they should be because of some factors such as the Carbon Dioxide reacting with the water. I can see that my prediction has come into effect with the gas nearly doubling with the mass. One example is 0.2 and 0.4. There results were only 2cm³ off each other.
One problem that I thought could have affected the results was that not all of the carbonate was released from the mini tube. It can either get stuck at the collar of the tube or inside the tube. Another matter is that I have to put the bung on straight away. If there is even a small time limit, gas could be lost. I shall take these points into account in my method so that my results turn out as accurate as possible.
Results
For each result that I did I had three results and then took an average. I then plotted two graphs. One of the graphs was for an average volume against mass and the other was for all the volumes against the mass. Because I had spare time as I had finished my chosen masses I decided to investigate some more masses. These were:
I decided to change my result table as I took an average result to make the experiment fairer. This is because one result could be far different from another even though they are the same masses. All of my averages are up to two decimal places so that the results are fair.
My results are shown in the tables below:
Below is a table for extra results that I obtained:
The results that are in a red font are within ten percent of the predicted value.
My results are plotted below:
Conclusion
From the results of my investigation I can conclude that if you double the mass of the carbonate then the amount of gas given off will also double. I know this with due to the theory which states this. I have shown the calculations below:
CaCo + HCL CaCl + Co + H O
1 mole 1 mole
100g 24,000 cm³
1g 24000 ÷ 100 = 240 cm³
0.1g 240 ÷ 10 = 24 cm³
0.2g 24 x 2 = 48cm³
0.3g 24 x 3 = 72cm³
0.4g 24 x 4 = 96cm³
0.5g 24 x 5 = 120cm³
0.6g 24 x 6 = 144cm³
0.7g 24 x 7 = 168cm³
0.8g 24 x 8 = 192cm³
0.9g 24 x 9 = 216cm³
1.0g 240cm³
As we can see from the information above if you double the mass, the amount of gas given off also doubles. For example:
0.5g of Calcium Carbonate gives 120cm³of gas
1.0g of Calcium Carbonate gives 240cm³of gas
Due to this theory my graph is a straight line graph as it is directly proportional.
My results were very accurate as the tables and graph shows on the previous pages. Seventeen of my twenty seven results were within ten percent of the predicted values. Six of the nine averages were also within ten percent of my prediction. The other results are within twenty percent of what the results should have been. As I predicted, my graph is a straight line through the origin. I do not think that I will need to repeat my results another time as they are rather accurate.
My results are not 100% accurate compared to my predictions due to some experimental errors. These could be the gas dissolving in water, not all the powder leaving the ignition tube or not collecting the exact amount of calcium carbonate powder as it is hard to get this exact mass. There was only one result that was slightly anomalous. This again could be from the results of the experimental errors mentioned above.
Evaluation
Using the method I have written I carried out the experiment and obtained some rather accurate results. Again I do not think I shall have to repeat my results as my prediction and results agree. There is only one slightly anomalous result which I could have done better on. But as a whole I think my results were accurate as many of them were in ten percent of what they should have been. If I could improve on anything I think I could have put the bung on the flask faster or even try and get a more accurate result for the powder and acid. I do think that I have collected enough evidence to support my conclusion. Due to my scale of results and extra results I do not think that I could do more to prove my prediction.
