Prediction
I predict that as I increase the sulphuric acid the rate of reaction will increase. I think this will happen because as I increase the concentration I am increasing the amount of particles in the vessel. If there are more particles there is a higher probability of head on collisions and so the rate of the reaction will increase. If I increase the the amount of sulphuric acid from 1 mole to 2 moles keeping other variables constant then the rate of the reaction will double too. This is a visible sign that the rate of reaction is increasing.
Although I can’t keep the temperature constant for the duration of the experiment. This is because it is an exothermic reaction, I can record the tempreture at the beginning and end of each reaction for additional information therefore making my results more accurate.
This experiment is a REDOX reaction, and I can explain what is happening in more detail by using an ionic equation.
Mg (s) + 2H+ (aq) → Mg2+ + H2
I can now see that the Magnesium gains electrons or gets oxidised also the Hydrogen loses electrons or reduces. I also don’t need to include the sulphur as this is a spectator in the reaction and doesn’t change.
Safety
When I carry out my experiment I will make sure that:
- I wear safety goggles at all times
- All bags and coats are kept at the side of the classroom and stools are stored under the desks.
- Long hair is tied back.
- There are no obstructions in the classroom.
- All dangerous acids, chemicals etc. are treated with care.
- All other laborotary rules are abided by.
Equipment
Here is a list of all the equipment I will need to carry out my experiment.
Measuring cylinder
Scissors
Test tube
5 sets of 5cm3 sulphuric acid in concentrations of 0.5M, 1.0M, 1.5M, 2.0M, 2.5M .
5 pieces of magnesium of a length of 1cm each.
Ruler
Thermometer
Stop watch
Method
-
Measure 5cm3 of sulphuric acid, of concentration 0.5M into a test tube and take the temperature.
- Add a 1cm piece of magnesium into the test tube and start the stop watch.
- Wait for the reaction to finish stop the stop watch and take the temperature.
- Repeat the experiment increasing the concentrations 1.0M, 1.5M, 2.0M, 2.5M.
- Record all results in a table.
- Take three repeat readings at each concentration.
Fair Test
To ensure that I am carrying out a fair test I must make sure that some variables are kept constant. The surface area of the magnesium could affect the accuracy so all 5 pieces of magnesium must be the same surface area and length (1cm).
I will keep the starting temperature of the reaction consistant but due to the fact that this is an exothermic reaction I can not control the temperature change throughout and at the end of the experiment so I will take the temperature at the beginning and end of the experiment.
I will make sure that the volume of each concentration of sulphuric acid will always be 5cm3.
Results
S.T = Starting Temperature
F.T = Finishing Temperature
Rate of a reaction = 1 time 1000
Analysis
I found from my results that as I increased the concentration of sulphuric acid the rate of reaction increased too. I think my results followed my prediction to a certain extent and I can explain what took place using the collision theory. As I increased the concentration there were more particles, so there was a higher probability of head on collisions so the rate increased. From my graph I I can see tat this is true because the time taken for the experimentto take place wadid increase steadily. I also said that if doubled the amount of sulphuric acid I doubled the amount of particles in the vessel, whish I have proved to be true. I thought this would mean that the rate of reaction would double too. When I processed my results I worked out the rate of each concentration using the average time.This was not true, from 0.5M to 1.5M the rate almost increased two times the original. Whereas from 1.0 to 2.0 the rate did not manage to double. I can explain this because the reaction was exothermic so energy could have been lost as the reaction progressed.
