Step 1:
I placed the conical flask on the paper, and drew a cross on the paper.
Step 2:
I collected all of my equipment, then using a clean 50cm³ measuring cylinder I measured 50cm³ of Sodium Thiosulphate. After this I got the small measuring cylinder and measured 5cm³ of Hydrochloric Acid. Then I added the Sodium Thiosulphate and the acid together into a conical flask which totally measured 150cm³. Then I just waited for the solution to go cloudy, till you can’t see the cross on the paper.
Step 3:
Now that you have completed the first 2 steps, you can clean the apparatus that you were using. Which is the 50cm³
measuring cylinder also the conical flask and the 10cm³ measuring cylinder. Now you must use the second 50cm³ measuring cylinder and measure 10cm³ of water as well as 40cm³ of Sodium Thiosulphate and 5cm³ of hydrochloric acid. This must be added to the conical flask in the following order: water, sodium thiosulphate and then the Acid last. This must be timed and when the cross disappears you must stop the stopwatch.
Step 4:
Again the apparatus must be cleaned and this time you measure 20cm³ of water also 30cm³ of Sodium Thiosulphate and the same volume of 5cm³ of hydrochloric acid. Once this part of step 4 has been completed you may add the water to the conical flask followed by the Sodium Thiosulphate and then the Acid, and then start the stop watch and once the solution has turned cloudy i.e. (you can not see the cross any longer) you must stop the stopwatch.
Step 5:
Again following the same procedure clean all of the equipment used. Once you have cleaned all of the equipment, you may start the next step. This is started by measuring 30cm³ of Water then 20cm³ of Sodium Thiosulphate and then finally keeping it the same 5cm³ amount of Acid. These must also be added to the conical flask in the same order and the one that goes first must be the Water followed by Sodium Thiosulphate along with the Hydrochloric Acid. Then it is time to start the stopwatch and wait for the solution to go cloudy and then stop it.
Step 6:
This is the last and final step and you will also need to clean all the equipment you have used. When you have completed the first part of the last step, you need to measure 40cm³ of Water also 10cm³ of Sodium Thiosulphate and 5cm³ of Hydrochloric Acid. The time for this must also be noted down once the solution starts to go cloudy and you can not see the cross on the paper any longer.
I know by increasing the temperature this will help increase the frequency of collisions, and particles collide with more energy. Increasing the concentration will help increase the frequency of collisions. If you make the particle size smaller it will increase the surface area and also increase the frequency of collisions. Increasing the pressure will only increase the frequency of collisions. The Catalyst and Enzymes which are the same do not need to run out and help the reaction to occur quicker by helping it so it does not need as much activation energy as needed in the first place with no catalyst.
I will have an independent variable which is the Sodium Thiosulphate which means I will be changing the amount of this particular apparatus. This is also shows that my dependent variable is the time. I will be finding out the time so this makes me conclude, that this is my dependent variable.
What makes the solution cloudy?
Sulphur actually makes the solution cloudy. Cloudy precipitate forms, it is difficult to tell exactly when the chemical reaction has stopped, as the concentration of sulphur is increased the quicker the solution becomes cloudy.
TABLE TO SHOW MY REACTION MIXTURE
I will do each experiment 3 times. I also will take the average time.
I will be doing the following to make the experiment as fair as possible, and show what I have found out and what I will keep
The same.
WHAT MAKES CHEMICAL REACTIONS GO FASTER?
Increasing concentration will lead to increasing the frequency of collisions.
SOLIDS- Making particles size smaller will lead to increasing the frequency of collisions and increase the surface area.
GASES- Increasing pressure will lead to increasing the frequency of collisions.
Catalyst will lead to less activation energy needed.
Enzyme will lead to less activation energy needed.
HEAT UP TO SPEED UP
If you increase the temperature, particles will collide more often with more energy.
SEEING THE PATTERN
You can carry this experiment out several times at different temperatures. All you need to do Is, heat the thiosulphate solution to a higher temperature each time, before adding a fixed amount of acid. Then you can measure the reaction temperature with a thermometer, once the reactants have been mixed, and the stopwatch started.
I will investigate the effect of changing concentration of sodium thiosulphate. I wil keep the temperature the same.
Low energy – head on No reaction
High energy – Flaring blow No reaction
High energy – head on
REACTION!
You need the right kind of collision before you get a reaction.
PRELIMINARY
I will need to do a preliminary experiment to choose the right concentration of sodium thiosulphate.
I chose medium to do the experiment with.
TABLE OF RESULTS
Table to show amount of sodium thiosulphate, and time taken for the cross to disappear:
ANALYSING
I have successfully completed my results which are shown on the graph. I can see that the cross takes longer to disappear in the lower concentration, sodium thiosulphate, and it disappears quickly in the high concentration sodium thiosulphate. As you can see from my graph, the straight line shows that with less amount of sodium thiosulphate, it will take longer for the cross to disappear. The curve shows that it takes less time with more sodium thiosulphate. I also had one suspect result, which is why I believe my results have been successful.
EVALUATION
By looking at my graph and table of results I would say that, my results are good because, all of the points are on the line apart from one (which is the only suspect result). I can see that, the less sodium thiosulphate, the more time it would take for the cross to disappear from sighting. However, I had one suspect result. This came from the testing I had with the concentration of 20 cm³ sodium thiosulphate and 30 cm³ concentration of water. This could have been due to the fact that there was a high decrease in time from, 157.3 to 97.7
