In summary.
Activation energy
The minimum energy needed to break bonds in the reactants for a reaction to occur
Catalyst
A substance which increases the rate of reaction but is not used up in the reaction.
Gas pressure
The pressure due to gas molecules colliding with the walls of the container they are placed in - each molecule hits a tiny area of the wall with a force
Rates of reaction.
A rate of reaction is the rate or speed at which a reaction takes place.
Reactions can only occur when atoms or molecules hit each other physically. So, anything that will increase the number of times the atoms in the reaction bang into each other will speed up the rate of reaction. If it decreases the number of times they smash into one another, the reaction will slow down.
If the reactants are more concentrated, then there will be more of them around, and they will hit each other more often. If they are less concentrated it will slow things down.
As a result, there is a direct relationship between the particles and their density, and the rate of the reaction. Whenever you have such a direct relationship, the result will be a constant increase in the rate of reaction, which will lead to a straight line on a graph.
Aim
The aim of this investigation is to see what effect changing the temperature has on the rate of reaction between sodium thiosulphate and hydrochloric acid.
Hypothesis
I think that the higher the temperature of the sodium thiosulphate the larger the rate of reaction.
Apparatus
- Conical flask
- Measuring cylinder X2
- Sodium thiosulphate
- Hydrochloric acid
- Kettle
- Water bath at 60°c
- Water bath at 80°c
- Paper with cross on it
- Stop clock
- Thermometer
- Ice
Diagram
Method
- I will use 50ml of sodium thiosulphate
- I will use 10ml of hydrochloric acid
- I will start the timer as soon as the reaction starts and stops when I can not see the X because the solution is yellow.
- I will do the experiment at five different temperatures. 0°,20°, 40° 60° and 80°
- I will repeat the experiment five times.
- I will work out the average and plot a graph.
- I will wear goggles because I will be using acids.
- To keep my experiment a fair test I will use the same amount of chemicals each time and make sure the same person collects it. Get the same person to time it and get another person to judge whether or not the reaction has finished or not.
Results
Here is the table of results and I will next draw a graph based on the averages.
Analysis
In my experiment I have worked out that as the temperature raises the rate of reaction rises this is because as the heat rises the atoms get more energy and more collisions happen and as they are moving faster more of the collisions are successful so the reaction is quicker. Using my graph I can see that as temperature rises rate of reaction rises and I can also see that the reaction is fastest between 0° and 20° but the reaction between 20° and 40° is almost the same as it. I think this is because at 0° the reaction is very slow and does not have much energy so a small increase in energy would be a large increase in the rate of reaction. The slowest reaction was between 60° and 80° I think this was because the particles already have lots of energy so you need a larger increase in energy to get a larger increase in the rate of reaction. In my hypothesis I said that as the temperature rises the rate of reaction will rise too after doing my experiment I have seen that my hypothesis is true and also I said concentration, having smaller pieces and using a catalyst speeds up rate of reaction so I think they would produce a similar shape graph and the results would probably be about the same.
My graph is at the back of the project
Evaluation.
I think my experiment worked quite well and fulfilled my aim and proved my hypothesis. I think my results were accurate because during my background research I found a graph for this experiment and my graph came out similar (Unfortunately I lost the graph because there was a power cut when I was researching.). my experiment could improved by testing it again using differ chemicals and see if the graph looked the same at the end I could also try it but this time change the concentration are try it using different catalysts which are known to speed up the rate of reaction. I think the results are good enough to write a conclusion from because I repeated the experiment five times and only got one strange result and that was not that different to the rest of the results. In conclusion I think the experiment went very well and the result came out well in the end as well. If I done the experiment again I would do the experiment over one day not two because I think that is why I got that one strange result.
Jason overman 10/05/2007 page of