Make sure the same amount of acid is used each time as it could affect the reaction because the more acid the more acid molecules there are to collide which could increase the speed of the reaction.
Do not treat one test differently to any of the others. i.e. don’t' shake the bottles - keep them still as it could speed up the reaction.
Make sure the temperature is the same it could affect the reaction because heat gives the molecules more energy so the speed up, making the reaction faster.
The timing needs to be the same each time so you can record accurate results on how the volume of gas changes in different strengths of acid.
Repeat the test 3 times to make sure your results are accurate and you can get good average results.
Apparatus list:
Delivery tube
Conical flask with the stopper.
Measuring cylinder
Hydrochloric acid. 25mls of: 1.5M (×3)
1M (×3)
0.75M (×3)
0.5M (×3)
0.1M (×3)
2g of Marble chips of roughly the same surface area.
Bowl of water.
Electronic scales
Safety glasses
Safety:
When you are doing the experiment be sure to wear eye protection and stand up, as if you drop the acid on you it can irritate and burn your skin.
Method:
1. Measure out 25mls of hydrochloric acid of the concentration you are testing and 2grams of marble chips.
2. Set up equipment as shown:
3. Partly fill up the bucket with water.
4. Fill up the measuring cylinder with water. Place your hand over the top and carefully put it upside down into the bowl of water trying not to let any air into the cylinder.
5. Put the 2g marble chips in the conical flask.
6. Add the 25mls hydrochloric acid and immediately put the stopper on the flask and hit the timer.
7. After 3minutes measure the amount of CO2 collected in the measuring cylinder.
8. Repeat the test using the 5 different concentrations of acid
*make sure you use 25mls of acid each time, keep the time to 3minutes, use 2grams of marble chips with roughly the same surface area each time and repeat each test 3 times all these factors will affect the results so they need to be kept accurate.
Results table.
Averages results table.
Rates of reaction.
*Rate of reaction = volume of CO2 produced (cm3)
Time (seconds)
0.1M = 1.3 = 0.0072 ml/s
180
0.5M = 12.2 = 0.067 ml/s
180
0.75M = 25.8 = 0.143 ml/s
180
1M = 75.2 = 0.417 ml/s
180
1.5M = 91.0 = 0.505 ml/s
180
Analysis.
In my averages table of results I noticed that as the concentration of hydrochloric acid got higher the amount of CO2 produced got higher, proving the collision theory which is the particles has to collide for a reaction to occur, to be right, because the higher the concentration of acid the more particles there are therefore there would be more collisions making the rate of reaction faster, letting of more CO2 in the given time of 3minutes.
On my graph of averages I have one anomaly which I have circled for 1 molar of hydrochloric acid. I would have expected the volume of CO2 produced would have been lower than 75.8 ml I would have expected it to be more like 60 ml. On my graph of results you can see all of my one molar results were all anomalies. This could be due to the concentration not being accurate which would affect it by there being more particles to collide which would speed up the reaction, the marble chips having a different weight or surface area, or the temperature being higher giving the particles more energy to move around and collide more again making the rate of reaction higher.
Conclusion.
From my results I can conclude that the higher the concentration of hydrochloric acid the volume of CO2 produced in 3 minutes increased. This supports my scientific research. I found that for a reaction to take place you need particles to collide, this is called the collision theory. The more particles there are, the more collisions there are, which speeds up the rate of reaction. The higher the concentration of acid, the more particles there are in the same volume, there are more collisions, so the rate of reaction increases.
I predicted that the higher the concentration of hydrochloric acid the more CO2 would be given off. My results prove my prediction correct. You can see as the concentration got higher the volume of CO2 increased with it.
Evaluation.
I am happy with my investigation overall. I only had one set of anomalies, which next time round I would avoid by making sure the concentration was correct and by making sure the temperature was the same, I would also make sure the marble chips were the correct weight. The rest of my results went very well and were accurate proving my prediction and scientific research correct. I felt I worked well, but next time I would give myself more time to double check everything to avoid more anomalies. I found in the end that the higher the concentration of hydrochloric acid, the volume of CO2 increased.
