# The Effect of Temperature on the Rate of Reaction Between Sodium Thiosulphate and Hydrochloric Acid

I predict that as the temperature is increased the rate of reaction will increase. This means that the graph drawn up in my analysis will have positive link so it will look something like shown below, and will probably be curved as the increase in rate of reaction will not be exactly the same as the temperature is increased so the graph will look something like this.
This can be justified by relating to the collision theory. When the temperature is increased the particles will have more energy and thus move faster. For that reason they will collide more often and with more energy. Particles with more energy are more likely to overcome the activation energy barrier to reaction and thus react successfully. For a reaction to occur particles have to collide with each other. Only a small percent result in a reaction. This is due to the energy barrier to overcome. Only particles with enough energy to overcome the barrier will react after colliding. The minimum energy that a particle must have to overcome the barrier is called the activation energy. The size of this activation energy is different for different reactions. If the frequency of collisions is increased the rate of reaction will increase. However the percent of successful collisions remains the same. As this is an exothermic reaction heat will be given out so if we are talking about bond braking or bond making, more bonds are being broken than they are being made so heat will be given out and after the reaction takes place the temperature should be more than before the reaction took place. The particles in a gas go through random collisions in which energy is transferred between the colliding particles. As a result there will be particles with differing energies. Therefore I predict that the graph will be curved Aim: - My aim is to see the effects of a change in temperature on the rate of a reaction. The reaction that will be used is: Sodium Thiosulphate + Hydrochloric Acid Na2S2O3 (aq) + 2HCl (aq) In my preliminary work I used a science software on a computer which does the experiment then I made a table a plotted it on a graph [image] From these results I will use 25cm3 of hydrochloric acid as the experiment is an exothermic reaction heat will be given out and on the first part of the graph there is a there is a big difference and at 25cm3 of hydrochloric acid they are nearly joined so if we use 25cm3 of hydrochloric acid it wouldn?t change the temperature as much if we used 5cm3 of hydrochloric acid. Subsequently at the end of the experiment our results will be more reliable Basic Method: I will first place out all the apparatus I need. I will set them up with the substances at different temperatures. As soon as I put Sodium Thiosulphate and Hydrochloric Acid in the flask), I will begin the stopwatch and time how long it takes for the reaction to occur. I will look from the top and wait for the cross to disappear. When that happens, I will stop the stopwatch and record the time. Safety test: I will have to do a few things in order to make my experiment safe. Firstly all stools should be tucked under the tables and bags should be out the way (so no one will fall over them when not in use. I am using a kettle so I wouldn?t open the lid when the water is boiled as the steam could burn the skin for example. Goggles would be worn. After the beaker is heated I will use a folded up paper and wrap it around the beaker and hold it tightly at the end (to make sure I don?t find it too hot and let go of it). Detailed method: The temperatures I am going to use are 15, 30, 45, 60, and 75 degrees Celsius. I will use this range because it seems like a good temperature to use and I will get a wide variation of results. I have started with 15 degrees because that is quite a low temperature so I can see the difference of results. I will need to get an average of a few results of the same temperature, to get meaningful results. I am going to use 50ml of Hydrochloric acid, 20ml of Sodium Thiosulphate and 0ml of water. I will make accurate measurements. I will do this by using a pipette or a burette (To measure 50ml of Sodium Thiosulphate I will use a burette to measure this and 20ml of Hydrochloric acid I will use a pipette to measure it, to measure 5ml of distilled water I will use a 100ml measuring cylinder). Fair Test ? In order for my findings to be official the experiment must be a fair one. I will use the same standard each time for judging when the X has disappeared. I will make sure that the measuring cylinders for the Hydrochloric acid and thiosulphate will not be mixed up. The amount of Hydrochloric acid will be 25 cm3 each time, and the amount of thiosulphate will be at 50 cm3 and the water will be 0 cm3. During the heating stage of the experiment, a blue flame will be used throughout. Also the same Bunsen burner and gas tap will be used to maintain continuity. All of these precautions will make my final results more reliable so the test would be a fair one. Using my preliminary experiments I decided on using the following apparatus: 1 thermometer 1 beaker 2 measuring cylinders 1 conical flask 1 stopwatch 1 kettle X board 1 pair of tongs 1 pair of goggles 1 pipette 1 burette For me to complete my experiment I will need to do the experiment in the following order: - 1. Fill the burette with the thiosulphate and then put it in a beaker. I am using a burette instead of anything else, as it is more accurate so at the end I will get an accurate reading. 2. Secondly get the pipette and fill that with hydrochloric acid. I have used the pipette for the same reason I used the burette, as it is more accurate than anything else. I didn?t use a burette as the pipette has only one reading which is 25cm3 and that is how much hydrochloric acid I am going to use 3. Now I am going to heat up the water in the kettle, as we need to get the hydrochloric acid and the thiosulphate to a certain temperature to get the results that we need. We are not going to combined the two chemicals then heat it up as it will react so we need to heat them up and then combined them . 4. After it is heated up I will get a conical flask and combined the two chemicals. 5. While it is reacting I will time it and see how long it will take for the x to disappear when it does I will stop the stopwatch and record the reading I will do this until I have done all the temperatures that I need to do twice to get an accurate reading of my results. Conclusion == From my set of results I conclude that temperature does affect the rate of reaction as the higher the temperature the lower the activation energy. I can see this from my table as for my lowest temperature, which was 15 degrees Celsius I got 120.5 seconds and for my highest temperature that was 75 degrees Celsius I got 4.5 seconds. [image] This is my finished set of results that I turned into a graph as you can see the lower the temperature the longer it took to react. This is because there is a higher temperature and the Thiosulphate and the hydrochloric acid will have more energy, and this will cause them to move around more. Furthermore chemical reactions need collisions to occur and if the particles are moving around quickly there will be a higher rate of collisions also the particles need to hit each other at a certain velocity to make a reaction occur and this will only happen at higher temperatures. At the lower temperatures that I did it was more difficult to get the certain velocity and react and only some were able to get the speed and react that is why the reaction took place over a long period of time. At 15 degrees Celcius the reaction took a very long time to occur. This was because there wasn?t that much heat and heat provides energy to the particles of reactants and if there isnt enough heat the particles wont move as much and need higher activation energy this is why it took longer the chemical reaction to occur. From 30-60 degrees celcius the time of reaction was quicker, as there was more heat present making the particles to collide more. Furtheremore the activation energy dropped. At 75 degrees celcius which was my last temperature the speed of the reaction was quicker as there was an incredible amount of heat but from comparison from the first two temperatures there was hardly anything between the time of the last two temperatures, meaning that the activation energy dropped but not as muh as the first two temperatures. My results support my prediction very well, as it proves that temperature does affect the rate of reaction. Evaluation The procedure of our group was correct when we were doing the experiments as we had three people in our group including me and one person used the stopwatch, the second heated the thiosulphate and the third person heated the hydrochloric acid. This is a better way to do it as if we kept on changing the person with the stop watch for example the times would have been different compared to if we kept the same person as the eye sight would be different so one person would see the cross disappear at an different time compared to another person. Also we done the chemical reaction multiple times and got an average out of this, as we done these results were more accurate and therefore we got accurate readings for each temperature also if we only done the experiment once we could have had a misreading as we might have timed it incorrectly. Also we could have used a different method, for example we could have had a torch and shined it under the conical flask and when the light stopped shining we would have stopped the stopwatch. But the only problem with this would have been was the lifeline left in the battery as it would keep on changing every time so it would make the test unfair.

The Effect of Temperature on the Rate of Reaction Between Sodium Thiosulphate and Hydrochloric Acid 9.2 of 10 on the basis of 1741 Review.