Stirring - By stirring it will force the particles to collide more which will make a reaction.
Equipment
Hydrochloric acid (0.25M, 0.5M, 1.0M, 1.25M, 1.5M, 2.0)
Sodium Thiosulphate
Conical Flask
Light Sensors
Measuring Cylinder
Paper
Stop Clock
Lamp
Bosses
Stand
Clamps
Fair test/ Variables/ Range/ Repeats
Fair test – This experiment has to be made fair in order for this to happen certain things have to be done right. The same person in the group has to measure the hydrochloric acid and the sodium thiosulphate.
Variables – You could change the amount of hydrochloric acid or the amount of sodium thiosulphate into the solution.
Repeats – We will do the experiment twice so we can repair the results to see if they are right.
Safety
To make the experiment safe each person in the class will be wearing a pair of goggles and an apron.
Prediction
I think that the higher the concentration of hydrochloric acid with the sodium thiosulphate will make the rate of reaction will be faster than a lower concentration of hydrochloric acid which will make the rate of reaction slower. That will mean that there will be more particles in the solution will means that they will collide more to make a reaction between the two substances. After we have done the experiment we will make a results table to see if my prediction is correct. We will also be putting together graphs to show the results better. From the two trials I did and put into the table I will be able to compare the two sets of results to see if they are right, and to see if my prediction is right.
Formulae
2HCl(aq) + N2S2O3 → S(s) + SO2(g) + NaCl(aq) + H2O
Method
- )Collect all the equipment together so you are ready to do the experiment.
- )Set up the equipment.
- )Collect the right concentration of hydrochloric acid and sodium thiosulphate.
- )Pour the two solutions into the conical flask while that person is doing that, another person should be starting the stop watch.
- )When the solution turns white and you cannot see the light sensor anymore stop the stop watch and write down the time into the table.
- )Wash the measuring cylinders and conical flask.
- )Repeat the method for a different concentration of hydrochloric acid.
Diagram
Analysis and Conclusion
We can obtain evidence by looking at the graphs which I have drawn and by the table I made. My prediction was correct as the concentration of the hydrochloric acid got higher the faster it was for the two chemicals to react with each other. When the hydrochloric acid was 2.0M that was when it was the quickest time to react. I only had a couple of anomalies which didn’t fit into my line of best fit.
Evaluation
The procedure that we used worked well but we did find a few problems when we did the experiment. For example when we collected the hydrochloric acid and the Sodium Thiosulphate we disagreed if the right amount of the acid was in the measuring cylinder. And the other problem was when the chemicals had reacted together we disagreed when it was time to stop the clock.
We could sort out them problems by just one person deciding if there was the right amount of hydrochloric acid or Sodium Thiosulphate in the measuring cylinder and then another person can decide when the two chemicals have reacted together.
The two trials which we did compared well because the times of the reactions were near enough the same there was no big differences between them.