Diagram
Method
To start off my experiment, I will collect all of our equipment and set it up. I will place the ceramic mats on the table then place the Bunsen on top of one and hook it up to the gas. The tripod will be placed over the Bunsen and then on top of that will be the gauze mat .I will then measure 35ml of Sodium Thiosulphate with the aid of the measuring cylinder and then tip that into the beaker. I will then measure 6ml of Hydrochloric acid again with the aid of the measuring cylinder but then leave the acid in the cylinder until the Sodium Thiosulphate is heated to a certain temperature. I will then turn the gas on and light the Bunsen. I will heat up the Sodium Thiosulphate to a temperature checking the temperature with the thermometer every few seconds. Once it is at that temperature I will lift the beaker off the gauze mat with the paper towel making sure that I don’t burn my hands. Once the beaker has been placed on the ceramic mat I will tip in the Hydrochloric acid. I will then start the clock and time it until the solution appears cloudy and I cannot see the black line through the solution. If the solution turns cloudy before I stop the clock I will take a few seconds off the clock. As I have chosen six temperatures to test I will repeat the procedure for all of them.
There will be one test on each of the temperatures. The range of temperature for the Sodium thiosulphate will each have a difference of 10degrees, this is so that we can obtain accurate results. The preliminary results were finding out the range of temperatures to use. The volumes used for the Sodium Thiosulphate and the Hydrochloric acid stayed the same throughout both the preliminary and the actual results. The amount used for the Sodium Thiosulphate was 35ml and the amount for the Hydrochloric acid was 6ml.I did not change anything during the experiment except for the temperature of the Sodium Thiosulphate.
Prediction
I predict that the higher the temperature the quicker the time it takes the Sodium Thiosulphate and the Hydrochloric acid to turn cloudy when mixed. I think this will happen because of the collision theory. The rate of reaction depends on how hard the reacting particles collide with each other. Particles have to collide in order to react. More collisions increase the rate of reaction. Temperature increases the number of collisions because when the temperature is increased the particles will move quickly. If they move quicker they will have more collisions.
Higher temperatures also increase the energy of the collisions, because it makes all the particles move faster. Increasing the temperature only causes faster collisions. So at a higher temperature there will be more particles colliding with enough energy to make the reactions happen. At low temperatures particles of reacting substances don’t have much energy.
Preliminary work
I decided to do some preliminary work because then I could see what temperatures to use and to see how the experiment worked. I decided on using these temperatures:
- 35degrees, 45degrees, 55degrees, 65degrees, 75degrees and 85degrees.
I chose these temperatures because they are not too high or low and are a good range to use.
These were my results:
I found out that the temperatures were affective and that I was able to achieve the temperatures but not keep them at that temperature. I think that the preliminary work is a good idea because you can find out any problems before you go out and do the real experiment.
Results
I only tested each temperature once as I wasn’t able to keep the solution at the temperature I wanted it at for long, therefore some of my results won’t be accurate.
Analysis
By changing the temperature the rate of reaction has been altered either faster or slower depending on the temperature. If the temperature is higher such as 62oC then the rate of reaction will be faster than if it was a lower temperature such as 33oC.For a reaction to take place between Sodium Thiosulphate and Hydrochloric acid particles must collide with each other and the collision must have enough energy. At low temperatures particles of reacting substances do not have much energy. However when the substances are heated, the particles take in energy. This causes them to move faster and collide more often. The collisions have more energy so more of them are successful. Therefore the rate of reaction increases. A reaction can also be made to go faster or slower by changing the temperature of one of the reactants. When Sodium Thiosulphate and Hydrochloric acid are mixed a fine yellow precipitate of Sulphur is formed. I found out that a reaction goes faster when the temperature is raised. When the temperature increases by 10oC, the rate approximately doubles. As we found with our results.
Evaluation
The rate of reaction has been changed with different temperatures. My conclusion stated that a reaction goes faster when the temperature is raised. If the temperature increases by 10oC the rate of reaction approximately doubles. Such as if the temperature were 35oC the time would be 0.23.91s and if the temperature was 45oC the time should be 0.22.78s.Some of my results were not accurate because I made an error when choosing my temperatures. Instead of using these temperatures 35,45,55,65,75 and 85, I should have used ones such as 33,46,57,68,71and 80.This is because once I get the Sodium Thiosulphate to a particular temperature it starts to fall so by the time I get the Sodium Thiosulphate and Hydrochloric acid mixed the temperature has gone down by a few degrees. Using my graph to see whether my results were accurate, I can see that from 65oC to 75oC one of my results has dramatically fallen from a few seconds and that might not make it accurate. The volumes could be measured more accurately by measuring the amounts and then weighing them to see whether they are equal. If I wanted to improve my experiment I would put the Sodium Thiosulphate into a water bath so that the temperature stayed the same or I could choose a better range of temperatures to investigate. I could also make both the Hydrochloric acid and the Sodium Thiosulphate the same temperature.
