Diagram 1 Diagram 2
Scientific Knowledge
Collision theory
This is when more particles are added to give a greater concentration. This is done because with there being more particles within the mixture there will be more successful collisions. We can also have more successful collisions by heating the mixture, stirring it and also increasing the concentration.
Kinetic Theory
When the Particles within the experiment are heated it will cause them to move much more quickly therefore there will be more successful collisions.
Preliminary Experiment:
This is one of the Preliminary I have chosen to do, this experiment shows us what happens when we use cold acid in one experiment and hot acid in another and the time difference that will occurs. This is because when we heat an experiment we are speeding up a reaction, because the particles have more energy there will be a greater chance of successful collisions. When we use cold acid it will take longer to react because the collision will not happen with a large amount of energy therefore making the reaction slower. This is how I will carry out the preliminary experiment
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I will set the experiment as shown in the diagram below. Using 25cm3 and 2 similar sized Marble Chips.
- I will repeat the experiment with Hot and Cold acid.
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I will then collect 80 cm3 of gas and time how long it takes. If it works the cold acid will take longer to produce the gas my theory will therefore be correct.
Results of experiment
These results prove my theory. Therefore I must control the temperature throughout my experiment.
Apparatus
Piece of paper with a cross drawn on.
Sodium Thiosulphate
Hydrochloric acid
Large Measuring Cylinder
Small Measuring Cylinder
Conical Flask
Stop Watch
Plan
- First of all I will set my experiment as show in my diagram. Using all the equipment above.
- When the equipment is set up I will add the amounts of Sodium Thiosulphate Hydrochloric Acid to my Conical Flask and will time how long it takes for the cross to disappear.
- I will repeat the experiment 5 times, each time diluting the mixture.
- When I have done this I will repeat the experiment again to make it a fair test and also to make my results more accurate.
- To make the experiment a fair test I will measure the Sodium Thiosulphate Hydrochloric acid and water accurately. I will also use the same piece of paper with the same cross on it.
Results
My results prove that my scientific theory is correct. My results show that as a decrease the concentration and dilute my mixture the reaction takes longer. It also shows that when I half my concentrations it takes twice as long to react this is because when we half the concentration we double the time because the reaction takes longer.
Conclusion
My experiment worked out very well I had no anomalies within my experiment I also found it very easy to do. The experiment has taught me a lot and I have proved my scientific knowledge is correct.
This experiment shows me that as I dilute my solution the time will increase, time will increase because the concentration of the Sodium Thiosulphate and the Hydrochloric acid will be diluted because of the water Therefore collisions will take longer to occur because they will not react well with the water. The results show me this because as reduce the amount of sodium Thiosulphate and increase the amount of water added the time becomes longer and the reaction takes longer to work. My Experiment shows me that my scientific knowledge is correct as I predicted that as I diluted the solution the time would increase. I also predicted that as I halved the amount of Sodium Thiosulphate the time would double. Therefore my scientific knowledge of Collision theory, this being when more particles are added to give a greater concentration. This is done because with there being more particles within the mixture there will be more successful collisions. We can also have more successful collisions by heating the mixture, stirring it and also increasing the concentration. My results also show Kinetic Theory is when the Particles within the experiment are heated it will cause them to move much more quickly therefore there will be more successful collisions is also correct.
My graph also shows me that there are now anomalies within my results because my graph shows positive correlation and all the points join together to make my curve. From my results I was also able to work out an average.
The reason for the increase in time as I diluted the solution is because higher concentrated solutions react at a faster rate because there are more particles in the reaction, so there is more chance of collision between these particles.
However when a low amount of concentration is used, the rate of reaction was not as quick. This is because when the water dilutes the acid there is many more water molecules added into the reaction. Which means collisions between these water molecules and other particles in the reaction are more likely to occur. And therefore slows the rate of reaction down.
Evaluation
My experiment was very successful and I found no anomalies within my results. I found that most of my scientific knowledge and predictions were very accurate my results show me this. My graph shows there are no anomalies within my results as my graph shows a perfect curve this proves my theory.
If I was to conduct this experiment again there are a number of things I could do to improve my experiment to give me more accurate results. I would measure my reacts more carefully using either a pupette or burette, as these would measure the volumes more accurately. It can sometimes be difficult to measure the perfect amount due to lack of time or a generous hand. I would also make sure I used the same cross, as I lost mine and had to make another. These were only minor problems and were easily overcome they didn’t effect my results thankfully. A final improvement would be to use a colorimeter to measure the cloudiness of the reaction this would give me very accurate results.
Other things that I could of investigated in order to improve my knowledge and work. I could see what effect temperature would have on the results within the experiment from my Preliminary work I would have predicted that if I heated the solution the reaction would have been quicker. I could also of changed the concentration of the constant in this case acid this would of caused the experiment to speed up because there would be more chance of successful collision because there would be more particles then could of looked at the difference in the results.
Overall I am very pleased with my experiment and my results I have found ways to improve my experiment if I had to ever do it again.