How does concentration affect the speed of the reaction?
If there is a higher concentration of a given substance the chemical reaction is quicker. The experiment we did to test this was to add calcium carbonate rocks to hydrochloric acid. In one test tube we had 5ml of acid and in the other we had 7ml of acid. The result was that the one in the 7ml of hydrochloric acid dissolved faster than the other one with only 5ml of acid.
How does surface area affect the speed of the reaction?
A larger surface area provides a quicker reaction. The experiment we did to test this was to take 1 teaspoon of calcium carbonate powder and add it to 5 ml of htdrochloric acid in a test tube and take a rock (which had a smaller surface area) and add that to 5ml of acid in a different test tube. Even when the powder had finished reacting, the rock was still fizzing away. The powder, with the larger surface area, had a much faster reaction.
How does temperature affect the speed of the reaction?
we found that the colder the liquid is, the faster the reaction occurs. The experiment we conducted in order to test this was heating up one test tube with 5ml of hydrochloric acid in a beaker of water and keeping the other test tube, also with 5ml of acid, cold. The hot one was 30 degrees Celsius and the cold one was 25 degrees Celsius. Then we added a teaspoon of calcium carbonate powder to each test tube and the cold one reacted quicker. We were very surprised by our results and when we asker our teacher, she said that our results were incorrect and that in fact, the hot one should have reacted faster.
Detailed question-
How does concentration affect the speed of the reaction?
Observations and results
- Both acids fizzed immediately when the acid was put in to them.
- They both became a white liquid that looked a bit like milk after the fizzing had stopped.
- The more concentrated acid had a faster reaction.
- All three trials had similar results.
Data
In the table below is the data from our experiment
![Data table](https://amchemistryblog.wordpress.com/wp-content/uploads/2010/05/table.png?w=450&h=281)
Conclusion
My hypothesis was that the more concentrated liquid would have the fastest reaction because I thought that the more acid there was, the quicker the powder would dissolve. If the acid was diluted, there would not be as much of it to help dissolve the powder. This proved correct as the 10ml of acid only took an average of 14.3 seconds to finish reacting whereas the diluted acid, with 5ml of acid and 5ml of water, took an average of 22.6 seconds to finish reacting. I think we got these results because of the reason I stated above, that the more acid there is to help dissolve the powder, the quicker the reaction is.
Some errors that were in this experiment were the following:
- The timing was not very accurate. We used stopwatches and probably did not start at exactly the right time or stop at the right time. It was quite hard to see when to stop because you could not always see the bubbles because it was a white liquid and hard to see. This would have affected our results.
- Our measurements might not have been completely accurate every time. We tried to use the same amount of powder each time- 1 flat teaspoon full- but it would still have varied slightly from time to time.
If we re-did this experiment, there would be several things that we would change to make this experiment more accurate. First of all, we would need to make the timing more accurate. This would be challenging because it is so hard to see the bubbles in the white liquid and to determine when the reaction is over. This could be achieved by videoing the experiment and then watching it in slow motion sso that we could determine the exatc time it took the reaction o take place. Secondly, we would need to make sure we always had the same amount of calcium carbonate powder. We could do this by weighing it instead of measuring it out in a teaspoon. Finally, we could do a bigger experiment with more trials so that we would have more data to draw a more accurate conclusion. All of these would make the experiment much more accurate.