Prediction: I think that as the amount of sodium thiosulphate is decreased and the volume of water is increased, the reaction time between it and hydrochloric acid will increase. This is because when concentration of a substance increased, it reacts a lot quicker due to there being more particles that want to react with each other. Reactions can only happen when the reactant particles collide, but most collisions are not unsuccessful in forming product molecules. Water has been introduced in this experiment to vary the concentration .If there is more water in the experiment, the less concentrated the sodium Thiosulphate will be, therefore slowing the reaction.
Plan of Experiment: To investigate how concentration of hydrochloric acid effects the reaction between hydrochloric and sodium thiosulphate.
The volume of Hcl is needs to be kept at 10cm3 constantly each time .start with 60cm3of sodium thiosulphate .last reaction will have only 10cm3of sodium thiosulphate.reactions will be completed when the x will disappears, for the timing to stop .three reaction will be made for each test ;this is done to gain different averages.
Diagram:
Apparatus:
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Measuring cylinder(50cm3)
- Small measuring cylinder
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Conical flask(100cm3)
- Sodium thiosulphate
- Hydrochloric acid
- Water
- Stop watch
- 2 beakers.
- Paper with “x” on it
Method:
- Put 1.15 of calcium carbonate into the test tube.
- Place the rubber bung connected to the gas syringe.
- Immediately start the stop watch and record the time.
- Repeat the experiment five times at different temperatures.
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At the following temperatures 10oc, 20oc, 30oc, 40oc, 60oc.
- You need to add some water to make part of the solution with the hydrochloric acid.
Safety:
! Take care when using chemicals and equipment during the experiment, especially hydrochloric acid.
! During the experiment I will not touch my eyes or mouth until I have thoroughly washed my hands.
! Wear safety goggles at all times during the experiment.
Fair test: I will keep the concentration of calcium carbonate the same and the hydrochloric acid will be different.
Results:
Conclusion: I can see from my experiment that my prediction is correct. I can see that as the concentration increased, the amount of gas produced was produced faster and more of it was produced.
Evaluation: If I had waited longer, and continued recording the results until the time was up rather than until nothing could be seen. As when nothing could be seen the experiment could still be happening but very little could have been happening. I should have also have recorded my results every 5 seconds rather than 10 seconds to get more results to analyze. I would make sure I used the all the same apparatus if I had to continue my experiment at a different time because different apparatus have different measurements and that would effect the experiment.
