I would repeat this method for any other temperature that needs to be brought down, using a waterbath with ice cubes. If the temperature should be higher then using the Bunsen burner the acid should be heated in beaker. A thermometer should be placed in it aswell. When the temperature has risen to the right point it should be removed from the heat and checked again. The actual temperature should then be recorded. The acid should then be poured into a conical flask and the Magnesium added. The same procedure needs to be then used, as above.
I will do each temperatures three times to make it more accurate. To test what gas was produced I will see if a splint makes a ‘pop’ when it goes into the gas filled cylinder.
Fair Test?
To make my experiment fair I will use an equal amount of Hydrochloric acid. I will make sure that in each experiment I use 50cm3 of Hydrochloric acid. I will use the same amount of Magnesium for each experiment, 0.06g. I will also repeat the test three times to get an average. This will make it much fairer as well as accurate. All the constants would also stay the same.
Diagram
Waterbath (To cool down temperature)
Bunsen burner (To heat up temperature)
Balanced equation
Metal + Acid Salt + Hydrogen
Magnesium + Hydrochloric Acid Magnesium chloride + Hydrogen
Mg (s) HCL (aq) MgCl (aq) H (s)
Mg (s) + 2HCL (aq) MgCl2 + H2 (g)
Prediction
I predict that the higher the temperature of Hydrochloric Acid is, the rate of reaction would be higher when in contact with Magnesium. A reaction goes faster when the temperature is raised. When the temperature increases by 100c, the rate should approximately double.
When the acid is heated there is more energy there so the reaction will go faster. Therefore the particles will begin to move around faster and there will be more successful collisions. The rate at which they travel becomes faster. The energy breaks the bonds apart. If the collision has no energy, no reaction occurs. The acid particles will bounce away from the Magnesium particles. The rate of a reaction depends on how many successful collisions there are in a given unit of time. When the acid is heated the particles will take in energy. The collisions, therefore, have more energy, so more of them are successful.
Observation
Results Table
Table continued . . .
Analysis
There is an obvious pattern in the results. I can see that as I increase the temperature of the acid the rate of reaction also increases. The time taken to collect 50cm3 of Hydrogen gas in the measuring cylinder decreases as the temperature increases.
On the graph, time against temperature, I can see that at first when the temperature is rising the time taken to produce 50cm3 of hydrogen gas, is also dropping fast. When the temperature reaches about 500c, time taken to produce 50cm3 of gas is quite fast, but time taken doesn’t keep falling as quickly as before. It gradually speeds up, unlike before when it speeded it up very quickly. By looking at the graph it tells me that as the temperature increases the time taken to produce the gas decreases.
On the graph, rate against temperature, I can see that there is a steady increase of rate as the temperature increases. But, when it reaches about 500c I can see that the rate shoots up very quickly until the temperature hits about 700c. From this I can tell that the best time for the acid to have successful collisions would be between 500c and 700c. When it hits 700c the rate is high, but increase at a much steadier speed.
The results to this experiment meet very well with my prediction. I predicted that higher the temperature of Hydrochloric Acid is, the rate of reaction would be higher when in contact with Magnesium. A reaction goes faster when the temperature is raised. This is exactly what I found. When the acid is heated there is more energy there so the reaction will go faster. Therefore the particles will begin to move around faster and there will be more successful collisions. The rate at which they travel becomes faster. The energy breaks the bonds apart. Effectively this is what happened. I saw during the practical and also after the practical, when I drew up the table and the graphs I drew, that as the temperature grew higher the rate of reaction also was getting higher and the time taken for 500c hydrogen to be collected was decreasing. So as the temperature grew, time taken to collect the set amount of gas took less time.
The collisions were successful because of the temperature, which caused the gas to be collected much faster, than when we were collecting it when the acid was at 200c than when it was at 600c. When the temperature was higher there was enough energy in the reaction for the HCL particles to move around and collide with a great force. When they collided with the Magnesium molecules the reaction took place, as the bonds between the HCL particles broke and then the bonds formed together to make a different set of molecules, which brought together the HCL particles and the Magnesium particles. So the reaction takes place when Magnesium chloride and Hydrogen is formed.
Evaluation
My accurate were quite accurate. I did everything fairly so every test I did had the same amount of acid in it, the same amount of Magnesium etc. The pattern of results I got was exactly I had expected. I expected that as the temperature increased the time taken to produce the set amount of Hydrogen would decrease. Also that as the temperature increased the rate of reaction would also increase. My results were as accurate as possible. My results were accurate because I repeated each temperature three times.
When I looked at my rate against time graph I could see there was one anomalous result. It was when the temperature was 700c. Its rate was higher than it should have been. Looking at the graph and my line of best fit I predicted that the rate should be 1.3cm3 / seconds not 1.7cm3 / seconds as it reads on the graph. This result may have been wrong because of many reasons. It might have been a human error. The stopwatch could have been started a little later than it should have. All the other results met what was expected so I think it may actually have been a human error.
I didn’t really have problems with anything in the practical, but I could say that I found it hard to make sure that there weren’t any air bubbles in the measuring cylinder full of water, whilst I was trying to put it under the water in the tub. That bit was difficult, when I put the measuring cylinder into the water I somehow got some air bubbles in it. I had to do that bit very carefully.
The results could have been improved with very minor adjustments, like I could have used a syringe to measure the acid out much more accurately, instead of a measuring cylinder. It would be time consuming but very accurate and precise. I could also have made my results even more accurate by repeating the whole experiment three more times, to make six in total, to get a much better average.
I could also have used other methods to calculate how it’s affected when the temperature is used as an important variable. I could have used the precipitation method. But I don’t think it would be as accurate as the method I used.
My results were quite reliable because they were done fairly and very accurately.
