My prediction is made clearer by the diagrams below which will show the particle theory.
Apparatus
- Measuring cylinders
- Boiling tube
- Ruler
- Stop Watch
- Magnesium ribbon
- 2 molar hydrochloric acid
Plan
First I will set up the experiment then I will put 30cm cubed of hydrochloric acid inside the boiling tube, no water will be added for the first part of the experiment. I will then put in a 1cm long piece of magnesium into the tube and I will start the stopwatch and I will see how long it takes the magnesium to react, before dissolving in the solution.
The experiment will be repeated again on numerous occasions but the concentration will be changed. I will do this by adding 5cm cubed of water to the solution but at the same time I will decrease the amount of hydrochloric acid by 5cm cubed. For example the second time I do the experiment, I will have 25cm cubed of hydrochloric acid and 5cm cubed of water. The experiment will continue like this until there is no hydrochloric acid and 30cm cubed of water in the boiling tube.
I will repeat the experiment in order to get some precise results. After repeating the experiments I will have two sets of results, I will work out the average and then I will plot the graphs.
The way that my experiment will be made fair is that only one thing will be changed and that is the concentration but all the other things that can have an effect on the outcome will be kept the same e.g. temperature and volume of liquid. This experiment will be done at room temperature therefore the temperature is the same all through the experiment. The same size of magnesium ribbon will be used every time.. (The second experiment which I will do will look at the effect different lengths of magnesium has on the rate of reaction.)
During the experiment, goggles will be worn at all times for safety precaution .
Results
From these results two graphs will be plotted, one on the average time and one on the Rate 1/t (X 10000).
Conclusion
From my results, the conclusion that I have reached is that the prediction which I made was correct and that the higher the concentration the faster the rate of reaction. This is shown on my graph because the lower the concentration got the slower the rate of reaction.
The reason why I got these results was because if the solution is made more concentrated it means that there are more particles of reactant knocking about between the water molecules that make collisions between important particles more likely to collide.
Also by increasing the concentration of reactants increases the rate of a reaction. This is because there are more particles in the same volume so more collisions are possible every second.
Evaluation
The experiment which I completed was done up to a high standard and the results I got were quite good and seemed reliable as they backed up my prediction and the particle theory.
I think that the experiment was done in a very well because I didn’t get any irregular result.
If I had a chance to do the experiment, again I would make sure that I was working with someone because when I did the experiment I had to put magnesium in the solution and then start the stopwatch and this made the results less accurate, but if I was working with someone the results would have been more precise.
Another problem was that when I was waiting for magnesium to dissolve and stop reacting I was looking with my eyes so therefore sometimes the results I got would not be fair. Fairness in an issue like this can be found in a light sensor. The light sensor will pass through the boiling tube and the solution then send the results back to the receiver this would enable me to tell whether the magnesium was still reacting.
Another thing was that when the liquids were being measured they were not done accurately because there was a shortage of time so everything had to be done quickly and this caused the results to be less precise.
Overall, I think that this was a good experiment and the best that could have been done with the time and resources available.