Also stand up while doing experiment.
Prediction:
I think that the higher the amount of Sodium Thiosulphate (50cm3) the more likely the cross will disappear quicker. I believe this as, Sodium is needed to produce the Sulphur, and if there is a higher concentration of sodium Thiosulphate, then the chemical reaction will take part faster as there is more sufficient energy for the particles to react.
Plan:
To investigate what effect concentration of Sodium Thiosulphate has on the rate of reaction. The volume of HCL needs to be kept at 5cm3 constantly each time. Start with 50cm3 of Sodium Thiosulphate. Last reaction will have only 10cm3 of Sodium Thiosulphate, and water will be substituting the missing Sodium Thiosulphate e.g. 40cm3 – Sodium Thiosulphate is 10cm3 less than the original, so then 10cm3 of water is added.
Reactions will be completed when the X disappears, for the timing to stop. Two reactions will be made for each test; this is done to gain the different averages.
Step By Step:
First I will Gather the Equipment for the Experiment and Set them out.
I will draw a table in my book for the results.
I will use the Goggles to protect my eyes from chemicals
I will draw a Large Black Cross on A piece of white paper.
Place a Beaker over the cross.
I will Get the two measuring cylinders and in the large, measure out 50cm3 of Sodium Thiosulphate. With the smaller measuring cylinder measure out 5cm3 of HCL (High Safety Needed Here)
Mix the two Chemicals (Sodium Thiosulphate + Acid (HCL) in a beaker and start the timer.
Once the cross has disappeared to the naked eye, stop the timer and record my results.
I will do this process twice to get an average time.
I will then do this several times for 40cm3 of Sodium Thiosulphate, 5cm3 of Acid (HCL) and 10 cm3 of Water, 30cm3 of Sodium Thiosulphate, 5cm3 of Acid (HCL) and 20 cm3 of Water, 20cm3 of Sodium Thiosulphate, 5cm3 of Acid (HCL) and 30 cm3 of Water and 10cm3 of Sodium Thiosulphate, 5cm3 of Acid (HCL) and 40 cm3 of Water.
Fair Test:
To make this experiment a fair test, I have to always keep the amount of hydrochloric acid the same, the exact same time that I start the timer (e.g. As soon as I mix the solution) and the same overall amount of liquid in the beaker in all of the experiments.
Diagram:
Results:
Exp1|Exp2|Exp3|Exp4|Exp5
Sodium Thiosulphate Solution (cm3) 50 40 30 20 10
Distilled Water (cm3) 0 10 20 30 40
Hydrochloric Acid (cm3) 5 5 5 5 5
Time for cross to Disappear (1) (sec) 33 42 50 87 250
Time for cross to Disappear (2) (sec) 28 44 56 90 290
Evaluation:
The results above show that my prediction was correct for this investigation. I predicted that the more Sodium Thiosulphate there is in the
Conclusion: The experiments made were very successful and we had managed to complete the experiment fully and fairly.
The fastest reaction made was with no water, 50 cm3 of Sodium Thiosulphate and 5 cm3 acid (HCL). This reaction is very fast with a time average of 33 seconds. The slowest reaction made was with 40 cm3 of water, 10 cm3 of Sodium Thiosulphate and 5-cm3 acid. This reaction was very slow with a time of 4 minutes in average.
Improvements: The experiments were handled fairly but it could have been even fairer. Because the reaction was finished when the black cross on the paper disappeared and this is only seen by the naked eye. With the whole class doing this with different eye types, there is no exact fairness in the experiment.
For Complete Fairness we could have used a device such as a light sensor or something similar. The light sensor will pass through the flask; if the light was not seen or had been broken up into many fragments then we would stop the experiment. This will make the experiment fairer.
