Apparatus
- Gas syringe
- Hydrochloric acid
- Magnesium
- Measuring cylinder
- Bung
- Stop watch
- Conical flask
Safety
- Wear goggles at all time
- Do not run around the lab
- Wash hands after the experiment
Preliminary tests
- First of all I collected the equipment I needed.
- I then cut six 10cm strips of magnesium from the reel of magnesium.
- I then connected up my conical flask and my gas syringe.
- Next I mixed six different concentrations of hydrochloric acid and distilled water.
- I then poured the first concentration into the conical flask, added one strip of magnesium and put a bung on the flask.
- I then started the stop watch.
- Next I measured the amount of hydrogen being produced every 10 seconds by reading the measurements on the gas syringe.
- I then repeated the same experiment but with 5cm strips of magnesium.
Concentrations
- 50ml of hydrochloric acid. (2mol/l)
- 40ml of Hydrochloric acid and 10ml of distilled water. (1.6mol/l)
- 30ml of hydrochloric acid and 20ml of distilled water. (1.2mol/l)
- 20ml of Hydrochloric acid and 30ml of distilled water. (0.8mol/l)
- 10ml of Hydrochloric acid and 40ml of distilled water. (0.4mol/l)
- 50ml of distilled water. (0mol/l)
Using 10 of magnesium
Using 5cm of magnesium
Findings and changes I am going to make
From my preliminary results I have found that my sixth concentration cannot be used for my real experiments because it does not produce any hydrogen when reacting with magnesium. I also found that using 5cms of magnesium caused the reaction to go to slowly and that using 10cms of magnesium caused the reaction to go to quickly. Because of these findings from my preliminary results I have decided to not use the sixth concentration in my real experiment and to use 8cm strips of magnesium.
I thought that 10 seconds intervals between each measurement worked well and I am going to stick with it. I thought the first 5 concentrations worked well and I am going to use these in my real experiment.
Obtaining precise results
In my real experiment I am going to try obtain precise and reliable results. To make my readings as precise as possible I am going to start the stop watch 10 seconds before I drop the magnesium into the concentrations of hydrochloric acid so that I do not have to worry about starting the stopwatch.. I am also going to be very careful in pouring the right volumes and concentrations I am using. I will also be very precise with measuring the surface area of each strip of magnesium.
To make my results even more accurate I will repeat the experiment.
Concentrations
- 50ml of hydrochloric acid. (2mol/l)
- 40ml of Hydrochloric acid and 10ml of distilled water. (1.6mol/l)
- 30ml of hydrochloric acid and 20ml of distilled water. (1.2mol/l)
- 20ml of Hydrochloric acid and 30ml of distilled water. (0.8mol/l)
- 10ml of Hydrochloric acid and 40ml of distilled water. (0.4mol/l)
- 50ml of distilled water. (0mol/l)
Results
Below is a table to show the results of my experiment with concentration 1. (2moler)
Below is a table to show the results of my experiment with concentration 2. (1.6moler)
Below is a table to show the results of my experiment with concentration 3. 1.2mol/l
Below is a table to show the results of my experiment with concentration 4. 0.8mol/l
Below is a table to show the results of my experiment with concentration 5. 0.4mol/l
Conclusion
I have found that the more concentrated with hydrochloric acid the reactant was the faster the reaction was. The reason that this happened is because of the collision theory. This shows that for a chemical reaction to occur an effective collision has to take place between the reactant molecules. So, the more concentrated a solution is the more chance of effective collisions to take place because there are more reactant molecules in the same amount of space. This is shown in the diagram below. All the reactant molecules are rushing about and are colliding with each other and in the more concentrated solution there is more reactant molecules which means there will be more collisions.
This is shown in my results. From my graphs you can see that the more concentrated the solution was the steeper the graph was. This shows that the reaction was faster. My prediction was if I half the concentration of the reactant then the reaction will take twice as long. When the concentration was 2mol/l the reaction took 90seconds and when the concentration was 1.2mol/l the reaction took 90seconds. This result is not completely accurate because 1.2mol/l is not exactly half of 2mol/l. But I took this into account and if the concentration was 1mol/l the reaction would have been slightly slower and would have taken around 80seconds.
Evaluation
The accuracy of my measurements were excellent. I know this because in both my runs of the experiment the results were very similar. The errors I could of made when obtaining my results could have been adding slightly too much of hydrochloric acid which would of increased the concentration or there could have been water in the gas syringe which would of made it stick when measuring the hydrogen. I do not think these happened though because my results were good.
There are no major anomalous results in my experiment. I know this because my all my results fit closely to my graphs. I believe this is because I carried out m experiment carefully and made sure I did not make any mistakes which could of lead to and odd results.
The only problem that I came across in my experiment was the amount of time I had to do it in. I overcame this by doing some of the experiment in my lunch hour. The only problem that arose in my method was reading the amount of hydrogen being given off from the syringe. This was a weakness to the accuracy of my results. I believe that the strengths in my method were the organisation of my equipment and the measuring of my solutions.
My results seem very reliable but there is some ways in which I could of made them more reliable. I could of got somebody else to take the stopwatch and tell me when to read the measurements from the gas syringe. This would have been much more efficient. I could of also done more repeats to make my results more reliable.
I think that my results are sufficient to form a firm conclusion because they show clear trends in my tables and in my graphs. I believe I have sufficient evidence to form a firm conclusion but to be sure I should do more repeats.
Further work I could do is to try more concentrations of hydrochloric acid.
