What will you change in your investigation?
I will change in my investigation the temperature of the Sodium Thiosulphate; this is the main aim of the experiment. I will change the temperature of the Sodium Thiosulphate to find out the effect of temperature on Sodium Thiosulphate when mixed with Hydrochloric acid, or see the rate of reaction when heat the Sodium Thiosulphate to various temperatures.
How will you make your investigation safe?
I will make my investigation safe by ensuring that a pair of goggles will be worn throughout the entire investigation, this will be done to make sure that the eyes are protected and no chemicals go into the eyes. Also when handling hot beakers I will make sure that a pair of tons will be used, this is because I do not want to burn my hands and by using tongs this will ensure that I don’t burn myself. Also I will use a gauze and a heatproof mat while heating to avoid any damages to the surfaces and equipment.
What is the smallest and largest value you will measure?
The smallest value in the range will be : 20 ‘C
The largest value in the range will be: 60 ‘C
How many results will you take within this range?
I will take 5 results within this range, as this is a sensible number. I will take one every 10’c
Do you need to repeat any measurements and take an average?
Yes I will be repeating each experiment three times to ensure that I get a sensible average from the results.
What have you learnt / found out?
I have found out many things from this investigation, but first I need to talk about how I decided the quantities I decided on (I.E. how much acid? How much sodium Thiosulphate) The quantities that I used where, 10cm3 of Hydrochloric acid and 40cm3 of Sodium Thiosulphate. I used these measurements because I thought that they were the most practical and sensible measurements to use, if I used 90cm3 of hydrochloric acid this would obviously be too much, as the 40cm3 of Sodium Thiosulphate would only react with 40cm3 of the Hydrochloric acid and will not completely make the marked on the piece of paper disappear. Thus resulting in an unsuccessful experiment, also if I used 200cm3 of Sodium Thiosulphate this obviously would be an imprudent volume to use. As the rate of reaction would take a long time to react with 10cm3 of Hydrochloric acid maybe would take under a day or maybe more, I do not have this time to do my experiment in as I only have one hour lessons twice a week of Chemistry, so the quantities of the hydrochloric acid and the sodium Thiosulphate had to be sensible. So I had to predict which ones would be most practical to use. Also I decided on testing the rate of reaction on temperature because I thought this would be most practical, as recording my results and plotting them in a graph would be rather difficult, also I have done before a similar experiment on temperature before so I had more confidence in this experiment. I wanted the method of the experiment to be followed in an order, so this would all be organised and so the experiment can flow thoroughly and easily. I decided to do each temperature from the lowest temperature (20 ‘C) do all three experiments on that temperature as it was room temperature then do the higher ones in order. I decided on this because the temperatures could vary if I do them all in different orders, also they might have to be done on different days and the room temperature can vary from day to day, so I did this in order to collect accurate results. I also decided to measure out the volumes of Hydrochloric acid and Sodium Thiosulphate out during the experiment to organize my experiment, so when one experiment was done I could quickly move onto to the next one that I had to do. Also I had to decide which range of temperatures I was going to do, obviously these had to be sensible and practical, if I any temperatures for the experiment over 70’C then the reaction would take place too quickly and I may not be able to take the results down. Also if I had a temperature under 20’C then the reaction would be too slow and I don’t want this to happen. So I decided on temperatures within those ranges of 20’c as the lowest and 60’C as the highest. I found out that the temperature can change the rate of reaction, the rate of reaction is the rate of formation of a product during a chemical reaction. This can all be based upon the collision theory, when you heat up a substance (in this case sodium Thiosulphate) the particles in the substance gain more energy, therefore are moving around faster, so when you mix it with another substance (in this case hydrochloric acid) the particles have more chance of a collision as the particles are moving faster.
Carrying out the Investigation
Labelled diagram of the apparatus you will use
Step by step method (what will you do?)
- Firstly I shall gather all apparatus that I need in order to complete the experiment
- Next I shall measure out 10cm3 of Hydrochloric acid into a measuring cylinder and 40cm3 of Sodium Thiosulphate into a measuring cylinder
- Pour the Sodium Thiosulphate into a conical flask, then place a thermometer into the conical flask and place the conical flask on the gauze.
- Turn the Bunsen burner on and heat up the sodium Thiosulphate to the desired temperature (20’c 30’c 40’c 50’c 60’c)
- After the desired temperature has been reached use a pair of tongs which is placed on top of a piece of paper marked with letter X
- Add the 10cm3 of Hydrochloric acid to the heated Sodium Thiosulphate. The stopwatch will now be started.
- When the mixture has turned sufficiently cloudy so that the letter X can no longer be seen the stopwatch will be stopped and the time will be recorded.
- The whole procedure is repeated three times to ensure accurate results
- Repeat at 30’C 40’C 50’C and 60’C
Table of Results
On piece of paper
Drawing Conclusions
Graph
On piece of paper
Calculations (this could be a gradient calculation)
What patterns or trends do your results show?
I have found from these results that there is a definite trend/pattern showing, from analysis In this experiment I have found that as the temperature is increased the time taken for the reaction to take place decreases, this means the rate of reaction increases as it takes less time for a reaction to take place, so more take place per second. This is because of particles reacting. In the experiment the time taken for a reaction to take place had a definite decrease the higher the temperature of the sodium Thiosulphate was, it decreased roughly around 20-50 seconds
How do your results support your original prediction?
My results do support my original prediction I made at the beginning of the experiment. I predicted that the higher the temperature the faster the rate of reaction. The results support my original prediction because it proves that as the temperature is increased the time taken for the reaction to take place decreases, when we did the experiment the higher the temperature the quicker the reaction took to take place. By looking at the graph you can see there is a definite decrease in the line, it shows negative coloration,
Explain what your results tell you using your understanding of science
My results show that the collision theory is correct, the results show that the higher the temperature of the Sodium Thiosulphate the faster the rate of reaction will be when it is mixed with the Hydrochloric acid, to back this up I need to look at the collision theory again 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 will react after colliding. If the frequency of collisions is increased the rate of reaction will increase. However the percent of successful collisions remains the same. So when you increase the temperature of a substance then the particles will move quicker, and when it is mixed with the acid the particles will react, so the quicker the particles are moving the more collisions will be successful resulting in a faster reaction.
