This reaction is called an endothermic reaction because the spark has to be applied for both gases to react and ignite. From the text on the collision theory I know that chemical reactions occur when particles from reactant A and reactant B collide with each other. The particles from both reactant A and reactant B must collide with a minimum energy called the activation energy. This reaction is called an exothermic reaction because when the particles are mixed they begin to react with each other at room temperature with out any heat or pressure applied to the chemicals.

From the collision theory I have learnt and discussed the collision theory will backup my prediction which I had predicted that the chemicals would react with each other with out any deliberate attention or force. This is an Exothermic Reaction This graph represents the amount of energy that should be going through the chemical reaction of the investigation that I am going to carry out. An exothermic reaction gives out energy to the surroundings. This means that the reactants must have more energy than the products have. The difference is the amount of energy given out. Exo = Out.

Thermic = Thermal = Heat This is an Endothermic Reaction This graph shows the opposite of what the amount of energy that should be going through the chemical reaction of the investigation that I am going to carry out. An endothermic reaction is the opposite of an exothermic reaction. In the endothermic reaction the products have more energy than the reactants. As the reactants become products, they gain energy from the surroundings.

102 seconds ANALYSIS Graph Patterns in My Graph The graph that I have drawn looks accurate and reliable because you cannot draw a line of best fit on the graph because the line on the graph is very accurate itself. I have found out that as the volume of hydrochloric acid is reduced the rate of reaction takes longer but as the hydrochloric acid is reduced the increase in seconds between each time 5mls of hydrochloric acid is reduced the rate of reaction increases more and more.

In other words the incline of the line doesn’t go up steadily it goes up a lot further causing the angle of the line to increase. I cannot not see or identify any odd results in my graph so I am happy to say that my results from the tests are accurate and reliable. Conclusion In my investigation I have found out that the rate of reaction will increase if such a chemical is reduced. I have also found out that the seconds will increase more and more in the gap between each 5mls of acid as you go along the graph the opposite way.

You will see that the angle of the line in the graph will increase more and more as you go along the graph the opposite way. From this I understand that if the volume of reactant A is reduced and is replaced with water to recover the loss of volume and they are mixed with reactant B the reaction rate will increase/be slower. When the volume of hydrochloric acid was reduced the reaction rate was slower. This was because there were not enough molecules in the hydrochloric acid to equal the amount of molecules in the sodium thiosulphate solution.

This led to the molecules in the hydrochloric acid to work even more harder to react with the molecules in the sodium thiosulphate solution. This caused the reaction rate to slow down because the molecules in the hydrochloric acid had to collide with more molecules from the sodium thiosulphate solution which led to extending the time for the molecules in the hydrochloric acid to collide with more molecules from the sodium thiosulphate solution. This is the reason why the reaction rate slowed down when the volume of hydrochloric acid was reduced. This is called the collision theory.

My prediction that I had predicted is accurate because I have written in my prediction that when the volume of hydrochloric acid is decreased and water replaces the volume of hydrochloric acid that has been taken away the reaction rate will be slower. And in the investigation that was carried out the rate of reaction decreased as the hydrochloric acid decreased and water replaced the volume of hydrochloric acid that was taken away Both of the statements mentioned above match each other so this must mean that my prediction that I had predicted was accurate.

I can now say that my results clearly support my prediction. EVALUATION I think that the investigation was a success because I had no problems along the way of my investigation. I think that my method is good, accurate and well detailed so that if someone else who had not done the experiment could follow my method and not get confused or stuck. I think my results are accurate and reliable because I did each test twice and worked out its average for a more accurate result.

I would say that my results are accurate and that the averages are correctly calculated because the line on the graph is presented as it was predicted to be presented. I believe that my results are reliable because when they are presented on the graph they make a correct declined curve as predicted. I found that the way I measured the rate of reaction was a bit unfair because it all comes down to the human reaction rate to press the stop button on the stop clock straight away when the cross under the flask is completely blotted out.

So the measuring of he tests may be a few seconds ahead or behind if your reflex is not as fast as you hope. And there was one big disadvantage of measuring the rate of reaction because when looking at the cross to see when it is completely blotted out your eyesight may not be as accurate and reliable. And if your eyesight is not up to standards than your results can be inaccurate and unreliable. Even though my results are accurate and reliable if I were to do the investigation again I would do each individual test five times to make sure I get a more accurate and reliable results.

This will make sure I get accurate readings to when I come to work out the average result of each individual test so that my results are sufficient enough for me to be able to reach a firm conclusion. I would also have used a laser over the top of the flask to measure when the cross has completely been blotted out by using a pad underneath the flask wired to a computer. The pad underneath the flask will stop the clock when the pad underneath the flask stops receiving the laser light when a certain amount of sulphur particles are formed in the volume.

When the sulphur particles have formed and the pad stops receiving laser contact then a current will go from the pad into the computer to stop the stop clock. I am also happy to confirm that the results I have obtained do not contain any odd results. Additional Experiment To extend my investigation in this subject I could use a catalyst for a reactant to see how efficient the catalyst is compared to other results as the catalyst is used again. This will tell me the efficiency of the catalyst.

For example I would mix 25mls of reactant A with the reactant B (catalyst) and measure the time it takes for the cross to be blotted out and record the result. Then I would repeat the experiment another 9 times and record the results. From the results at the end I would be able to see if the catalyst is deteriorating or staying the same. The aim of this experiment would be to find out if the catalyst is at all effected when it us used. You will be able to see this if the results are plotted onto a graph.