Size of Particle – When a particle is big in size the arte of reaction will be slow, but if it is small in size the rate of reaction is fast. When the size of the particle is small it has a large surface area, therefore the number of collisions will also increase with sufficient energy
If the marble chip is split up more of its surface area can react with the acid.
To measure the rate of reaction we will measure both volume of gas produced and the time taken for the reaction to complete. We have chosen to collect 40cm. We will know when the reaction has finished when the piece of magnesium has disappeared and also when 40 cm3of gas has been collected.
To ensure that the experiment is accurate the investigation will be repeated 3 times at each different concentration. This will provide us with a mean for the volume of gas collected and the duration of the reaction.
By repeating the experiment at each value we will be able to reduce the effects of each value we will be able to reduce the effects of anonymous results.
Apparatus
In order for me to complete this investigation I had to use the following apparatus.
The apparatus that I used were:
Gas syringe
A round bottomed flask
Rubber Tubing
Stopwatch
Magnesium ribbon (cut to 3cm each time)
Five different concentrations of Hydrochloric Acid
Thermometer
Measuring cylinder
Goggles
Method
This investigation will be carried out in a certain way so that it is accurate and I don’t make any mistakes. The diagram below shows how the apparatus should be set up so that I can perform the experiment.
I will explain a step by step procedure which I followed to carry out this investigation
- Collect all the right apparatus and set up the apparatus like shown on the above diagram
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Measure 10 cm3 of Hydrochloric acid of chosen mol(0.5 mol) using a measuring cylinder and pour into the round bottomed flask
- Add the magnesium to the flask and replace the rubber tubing quickly as possible and start the stopwatch
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Record the time it took to reach the target of 40 cm3 of Hydrogen gas
- Repeat the above 2 more times keeping everything the same each time.
- Now repeat all the above for mol of 1m 2m, 2.5m ,4m and 5m
- Clear up at the apparatus and put back all apparatus in their appropriate place
Results
From this results table I will now draw two graphs. My first graph will compare the average time it took to collect 40 cm3 of Hydrogen gas.
I will also draw another graph this will be on the rate of reaction and will be compared to the times it took for every reaction.
Analysis of Graphs
From Graph 1 and the results table I can see that as the concentration of Hydrochloric Acid (in Mol) is increasing so does the rate of reaction.
From Graph 2 we can see that as the concentration of Hydrochloric acid increases the time in which it takes to collect 40 cm3 of Hydrogen gas decreases.
When comparing the two graphs we can see that an anomalous result has occurred in the 4 molar solution. They are both circled on my graph and table.
Evaluation
My results were fairly accurate all except one at 4 mol which was an anomalous result.
I think that the anomalous result occurred because we did the 4mol last. At this time the beaker which were currently using had smashed accidentally. Therefore we had to change the size of the beaker as this was the only one left and this beaker was smaller than the previous one. The liquid in this case was taking up the shape and this reduced the surface area therefore the rate of reaction decreased. This resulted in an anomalous result.
I thought that there were limitations and errors which occurred in my investigation and prevented me from getting accurate results.
Firstly there were huge amount of Hydrogen were being lost when putting the bung and could have been prevented by using a flask which has a divider.
Secondly when we washed the contents after each trial water may have been present instead we could dry the beaker very well.
Lastly we missed out many different mol of Hydrochloric Acid. If I was to repeat this investigation I would investigate all the intermediate concentrations e.g. 0.5,1,1.5,2,2.5,3,3.5,4,4.5 and 5 . This wider range of values would improve the reliability of results and the ability to draw to a conclusion.
We could have extended our investigation by investigating other factors concerning Rate of Reaction. These could have been the following
- Temperature
- Surface Area
- Pressure
We could of investigated what the relationship is between each of these factors and see if the results produced this.
We could have investigated the rate of reaction on other substances like sulphuric acid.
Conclusion
From my results I conclude that my prediction is correct. My prediction was that if the concentration of Hydrochloric Acid increases therefore the rate of reaction should also increases this is because the number of collisions between the Magnesium and Hydrochloric acid increases so the time taken for 40cm3 of Hydrogen gas to be collected decreased therefore the rate of reaction increases.