Rates of Reaction Coursework.

* Catalysts also increase the amount of collisions per second because a catalyst gives particles a surface to attach to, this makes it easier for them to collide into each other.

The following theories proves to us that temperature, concentration, and surface area affect the rate of a reaction because.

* Rates of reaction are clearly explained through the collision theory. It explains to us that the rate of reaction depends on the amount of times the reacting particles collide with each other and how hard they collide into. We're told that particles have to collide with enough energy for a reaction to take place.

The kinetic theory explains to us that heat energy causes the particles in a liquid and gas to move around more rapidly, therefore creating more energy will result in this energy being used to break old bonds and to form new bonds. We're told that heat energy causes the particles in a solid to vibrate extremely quick, this causes the heat energy to be spreaded out among it's surroundings, this causes the heat energy to be transferred in between each particles.

* The particle theory also explains to us that the more particles that there is present in the same amount of volume the more closer the particles will be to each other. This means that the particles will collide more frequently into each other and the rate of the reaction will increase because there are more reactions per second.

Fair test.

In order for my test to be a fair test I will have look out for the following things:

* When the cross has disappeared completely out of sight then we know that a chemical reaction has taken place because when Sodium thiosulphate reacts with an hydrochloric acid, a yellow precipitate of sulphur is created. And this yellow substance of sulphur will eventually make the cross disappear. I should only stop the stopwatch when the cross has completely disappeared out of sight because that is when we know that the reaction is complete.

* I will have to be sure of that I use the same size conical flask I used to measure out the chemicals.

* I will have to be sure of that I use the same cross through out the entire experiment.

* I will have to be sure of that the measuring cylinders and pipette that I use for the sodium thiosulphate and hydrochloric acid don't get mixed up. If I fail to do this, this will result in that I don't get the accurate sets results that i wanted because their will still be remaining of other chemical particles in the cylinders.

* In order for my results to be valid the experiment must be a fair. I will use the same standard of procedure each time for judging when the cross has disappeared. This is judging whether the cross has disappeared completely our of sight by looking down directly from the top of the conical flask and immediately stopping the stopwatch when I am unable to see the cross completely. I will make sure that the measuring cylinders for the hydrochloric acid (2HCl) and the sodium thiosulphate (Na2S2O3) do not get mixed up. The amount of hydrochloric (2HCl) will be 5cm³ each time and the amount of Sodium thiosulphate(Na2S2O3) will start of with 50cm3 and will be reduce at each stage by 10cm3 and the amount of distilled water (H2O) will start of at 0cm3 and will increase by 10cm3 each stage.

* By using the exact Conical flask and paper with a cross marked on it I will be able to discover a relative measure of the speed of the reaction in forming the same amount of sulphur.

* I have to make sure that the hydrochloric acid I use remains at a fixed amount of 5cm³ through out the whole experiment because I am going to be investigating how the concentration of sodium thiosulphate affects a chemical reaction and this means that I must only change the concentration of the sodium thiosulphate.

Safety Precautions.

During my investigation I am going to take the following safety precautions:

* We should not eat or taste any form of substance. If we have any contact with a chemical, the part that has made contact should be washed immediately. Following those rules will prevent us from being poisoning or have any harm done to us.

* It is vital to keep a certain distance from the chemicals whilst a reaction takes place, as the outcome is Sulphur Dioxide, which is a poisonous gas and can be dangerous to us living organism. We should handle this experiment with great amount of care.

* A pair of goggles will have to be worn during the experiment in order to protect my eyes from any harm.

* I would strongly advice people to wear an apron to protect their skin and clothing because it prevents the acid making any sort of contact with your skin and clothing.

* If you have long hair you will have to tie it back, because it could be hazardous towards your safety.

* You mustn't run in the laboratory because it is an extremely dangerous environment because it has a whole variety of chemical and if you do run then you might knock chemical or run into another pupil which can cause a deadly accident or injury to you or other around you.

* You should never play or mess about with water or squirt chemicals at other students, as it may make contact with their eyes and skin and cause irritation or may cause something worse.

* You should always wash your hands after coming in with chemicals for health, safety and hygiene reasons, so that no chemicals are left on your skin. Because if there is remains of chemicals on your hands and you touch your eyes with your hands it may cause temporary blind and irritation which may lead to a long term effect.

Tools that I have used.

During my experiment I used the following equipments through out the entire procedure of my experiment, which are:

Tap where we get water from.

Digital stop watch to see how long a chemical reaction takes place.

Goggles for eye protection.

Conical flasks where all the experiment will happen.

Pipette to measure the chemical that we will use.

To measure fluids in cm3.

Pen to use it to record my results on a piece of paper.

Piece of paper with a cross marked on it that I used for my experiment.

Method.

In order for me to do my experiment I will successfully I will go through the following steps:

) I will wear a pair of safety goggles to protect my eyes from any harm.

2) I will clearly mark a black cross on the middle of a white piece of paper.

3) I will then place a 500ml conical flask exactly on top of the paper that has a cross clearly marked on it.

4) I will now measure 50cm3 of sodium thiosulphate using a 100cm3 measuring cylinder and leave it a side.

5) I will now measure 5cm3 of hydrochloric acid using a 10cm3-measuring cylinder and pour it into the conical flask.

6) I shall now have to prepare a stopwatch to measure the time for a chemical reaction to take place.

7) I will now pour the Sodium thiosulphate into the conical flask and at the same time start my stopwatch to record how long it takes for a reaction to take place. When Sodium thiosulphate reacts with an acid, a yellowish cloudy solution of sulphur is formed.

8) The sulphur solution that is formed eventually blocks the cross and I then stop the stopwatch.

9) The time taken for the cross to be blocked by the sulphur must now be written down on my chart.

0) These steps must now be repeated three times using 10cm3, 20cm3, 30cm3 and 40cm3of water and by lowering the volume of Sodium thiosulphate by 10cm³ each time. However the volume of hydrochloric acid must stay the same fixed rate of 5cm3 throughout the entire experiment.

1) Once you have both the preliminary results and the repeat results in hand, you will need to record them in a table showing how much of each substance was used and how it affected the rate of reaction between the sodium thiosulphate and the hydrochloric acid. Then you must work out the average time for each one.

Diagram steps of how I did the experiment.

Here is what the chemicals look like at the first stage of the experiment

At this point of the experiment a chemical reaction has taken place.

This is the final stage where the cross has been completely blocked by the new solution.

Results.

Here is a chart that I have recorded during my experiment.

Sodium thiosulphate 50 40 30 20 10

Distilled water 0 10 20 30 40

Hydrochloric acid 5 5 5 5 5

Time taken for cross

to disappear (sec) 57 74 83 110 364

Time 1st repeat 57 75 82 109 363

Time 2nd repeat 56 74 82 109 364

Time 3rd repeat 57 75 83 110 362

Average time 57 75 82 109 363

Analysis.

My results in the table above show the volume of substances, which I used in my experiment and the time taken for these substances to react with each other. I have also shown the average time. I repeated the experiment three times so that my experiment and my results would be more accurate. My results in the table above proves to us that my prediction was correct, because I predicted that by increasing the concentration of sodium thiosulphate it would also result in an increase of the rate of reaction. The collision theory also proves that my prediction is correct because it tells us that the rate of reaction is the amount of collisions between reacting particles in the particles per second. We already know that by mounting the concentration there will be greater amount of particles and this means that they are squashed up more, this will result with more collisions taking place because of the fact that there are more particles in a certain amount of area it will be easier for particles to collide with each other. I have also presented my results in the form of graphs, in order to make my results more understanding. This will also allow me to show that my results are similar to each other in a clear way. In conclusion my prediction was right because my results from the experiment agree with it.

Evaluation.

My evidence is extremely reliable, I state this because the experiment was repeated three times and this made the results even more accurate. For example I know that my evidence was very reliable because as you can see in the table above, my results were extremely similar to each other. My evidences were also supported by theories such as the collision theory and the kinetic theory. There were no irregular results in my experiment, because they were very similar as you can see in my graphs.

If I was to do this experiment again I would make sure I repeat my experiment more times then I did to this one, so that I would have a higher level of accuracy, and this would be clearly displayed in the results.