The reason for this is that some substances have extremely strong bonds which need more energy to break whilst others have weaker bonds which take less energy to collapse.
The effects of surface area:
The effects of concentration:
The effects of temperature:
2mph
25mph
In order to calculate the rate of reaction I will use this formula:
1
Average time
When sodium thiosulphate solution reacts with hydrochloric acid a solid is formed. The time taken for a certain amount of sulphur to form can be used to indicate the rate of reaction. In this experiment the effects of the concentration of the sodium thiosulphate on the rate of reaction is investigated.
Method:
1.
2.
Add the acid to the sodium thiosulphate and start the clock as you do so swirl the flask and place it on a piece of paper marked with a black cross.
3.
Look down at the cross from above. When the cross disappears from view stop the clock and note down the time.
4.
Repeat steps 1, 2 and 3 using different concentrations of sodium thiosulphate solution.
5.
Do all these steps three times to validate results.
Prediction:
I believe that as the concentration increases so will the rate of reaction. This is because from my research which is in my scientific knowledge I have seen that speed of a reaction increases with three thing and one of them is concentration.
Safety:
For safety reasons I will use the following:
1. Safety mat
2. Goggles
3. Apron
4. Gloves
Fair test:
In order to keep my experiment viable I will keep the following the same:
Temperature: this is because from my scientific knowledge I have learnt that temperature can change the speed of a reaction
Surface area: this is because from my scientific knowledge I have learnt that the surface area can change the speed of a reaction
Stop watch: this is because these may vary slightly from another one.
Same paper with cross: this is because the crosses may be of different sizes
The variable that I will be keeping the same is the concentration
Equipment:
Stopwatch
Measuring flask
Test tube
Paper with cross
Sodium thiosulphate
Hydrochloric acid
Results:
Conclusion:
From my graph I can see that as the concentration increases so does the rate of reaction. This goes in line with my prediction. However there are some anomalous results which could have been caused by human error. One example is the error of the human eye and human reflexes.
Evaluation:
If I had the opportunity of expanding this experiment I would expand it to cover other concentrations of sodium thiosulphate I would also try and see what difference the concentration of hydrochloric acid would make to the rate of reaction. Also would experiment what the other variables would do to the experiment.
In order to avoid the anomalous results I would connect a commuter to a light sensor and cover the light bulb with a box so no light is let out.