Na2S2O3+2HCI~NaCL+SO2+S+H2O
Equipment
- BEAKER FOR THIOSULPHATE
- TUBE FOR ACID
- PAPER WITH CROSS ON IT
- STOPWATCH
- REACTION VESSEL
Method
As I have chosen to change the concentration of the solution I will need to change the levels of both distilled water and thiosulphate. I will do this in ratios: (sodium thiosulphate:water)
*25:0 cm3
*20:5 cm3
*15:10 cm3
*10:15 cm3
*5:20 cm3
*0:25 cm3
I have shown this in a table below. When I put my solution in to the reaction vessel I will wait for the solution to go cloudy and stop the watch when the cross cannot be seen through the top of the beaker. The amount of hydrochloric acid (cm3) will remain the same throughout the experiment. Room temperature 21oC will ensure the same environment for the reaction (this is important because if it is hotter during one reaction period, the particles will gain more energy and collide more). This is a fair test.
Safety
For the safety of myself I will wear goggles throughout the experiment.
STEPS I’M GOING TO TAKE:
- Wear goggles
- Collect equipment and place on my working place
- Mix thio and water to the correct ratio and then place in reaction beaker.
-
Get 10cm3 of hydrochloric acid and add to reaction beaker
- Start the stopwatch and stop it when the ‘x’ cannot be seen.
- Dispose of chemicals in the waste jar provided.
Preliminary experiment.
To check if there would be any difference between the high and low concentration of thio and whether the results would happen in a reasonable time I performed a trial experiment to find out. I personally thought that 25ml of water with no thiosulphate would not react and the 25ml of thiosulphate with no water would react very quickly. These were my results for the trial experiment:
High concentration (25ml thio~0 ml water)-18.13 seconds
Low concentration (20ml water~5ml thio)-165.31 seconds
(I didn’t use the solution of 25ml water~0 thio because it didn’t react)
Now I knew this I conducted a more thorough experiment based on these results and compared them to my new results.
Test 1
Test 2
I then compared these results to the same experiment but with a stronger 2m acid checked the outcome.
When I compared these results to my old results for the 1m acid I found out that the solution took to react is around about twice as fast as the 1m acid. This shows that a higher concentration of acid and a higher concentration of thiosulphate will result in more collisions of the two particles and thus resulting in a faster reaction.
Conclusion
From my diagram you know that a higher concentration is needed to create a faster reaction. In diagram 1 you see that the thiosulphate is swamped by the water and that as the acid is only a 1m there is more water in the acid. There are 5 acid and 5 thio particles, which will result in a very slow reaction due to lack of collisions. In diagram 2 there are 20 thio particles, 10 water particles and again only 5 acid particles due to the weaker 1m acid. There is a much higher chance of collision in this solution due to the increase of thio giving the solution more particles to collide. In diagram 3 however I used a higher concentrated 2m acid with no water in it. There was 15 thio particles, 10 water particles and 10 acid particles. There is a good chance of a fast reaction in this solution due to the 10 acid and 15 thio particles, which will have a strong chance of collision. These experiments prove that a higher concentration of acid and thiosulphate will result in a faster reaction.
Evaluation
I felt that the experiment went fairly good but there are still a lot of points that could be improved on. We had some anomalies during our practical experiment such as the 15ml thiosulphate and 10 ml water. Reasons for this may be the person conducting the experiment forgetting to stir the solution or a miscalculating in the measurements of the two chemicals. The investigation could be improved by making sure all measurements were taken accurately. You could also make sure you stir all of the solution a certain amount of times (so it’s a fair test).
