result to a slow reaction.
Apparatus
Hydrochloric acid
Magnesium
Beaker
Ruler
Stopwatch
Measuring cylinder
Method
1. Measure out 50cm3 of hydrochloric acid.
2. Put the 50 cm3 of acid in the beaker.
3. Using a ruler measure 3cm of magnesium.
4. Put the magnesium in the hydrochloric acid starting
the stopwatch.
5. Stop the stopwatch when all the magnesium has
disappeared.
6. Repeat the experiment using different concentrations.
Fair Test
In order to ensure that my investigation was a fair test, the following were the kept the same:
1. Always measure 3cm of magnesium before you place it in the beaker which has hydrochloric acid.
2. Always measure 50cm3 of hydrochloric acid.
Safety Points
During the investigation the following safety procedures were used.
1. Safety goggles must be worn whilst using hydrochloric acid.
Observing
Analysis
My results show that as the concentration of hydrochloric acid decreases the reaction with magnesium takes a longer time.
My results confirm my original prediction which was the greater the concentration the greater the rate of reaction will be and the lower the concentration the lower the rate of reaction will be.
Looking at my results I can see that collision theory takes place as well, which made the results come out the way they did. The greater the concentration the greater the chance the magnesium and acid have of colliding with each other. When particles of acid and magnesium collide they either bounce apart or they react to form a new substance.
Collision theory explains how chemical reactions occur, and why rates of reactions differ. For a reaction to occur, particles must collide. If the collision causes a chemical change, it is referred to as a fruitful collision. Only a certain fraction of the total collisions cause chemical change: these are called successful collisions. The successful collisions have sufficient energy (activation energy. I have explained this in planning 2)
at the moment of impact to break the existing bonds and form new bonds. Increasing the concentration of the reactants and raising the temperature bring about more collisions. When a catalyst undergoes collision with the reactant molecules, less energy is required for the chemical change to take place, and more collisions have sufficient energy for reaction to react.
Evaluation
Although my method was quite good I think I should’ve completed 4 instead of 3 repeats. This is because I think it needed to be more accurate but I am happy with my method. I think there was one odd result when the concentration was at 20cm3. It was 6 minutes more than the one before. I think the reason for this was that I used more than one bottle of acid and another reason which I think caused this odd result is that some boys were mixing water with the bottles of acid.
I definitely think that there is room for some improvements. Firstly, I think that the magnesium should have been weighed on a very accurate balance which wasn’t available. Secondly I think that the magnesium should be cleaned using emery paper so it can remove corrosion.
Finally I think that the experiment could be repeated again by another method, probably using a balance to measure the mass of gas given off each 30 seconds. This will produce a higher quality and accurate experiment.
Planning 2
Activation Energy.
Activation energy in chemistry is the minimum energy needed to cause a reaction. A chemical reaction between two substances occurs only when a particle of one collides with a particle of the other. When they collide they may form a product whose chemical energy is higher than the combined chemical energy of the reactants. In order for this state in the reaction to be achieved some of the energy must enter into the reaction other than the chemical energy. This energy is activation energy. In gases, liquids and in solution, the particles move at different speeds, some move very slow and some move very fast. Particles must collide with enough energy to react.
