I found this graph in a book named “Chemistry for You.”
I also found a similar graph at
www.Learn.com.
Aim-
“To find how changing the concentration changes the rate of reaction.”
Prediction- I think that as the concentration increases the speed of the reaction will increase.
Reason- This is because as the concentration increases there are more particles and so there will be more chance of the opposite particles hitting each other
Quantified Prediction.
I think as the concentration doubles the rate of reaction will double.
Quantified Reason.
This is because as the concentration doubles, the number of particles double and so the chance of a collision doubles and so the rate of reaction doubles.
Variables.
Al the following alters my reaction-:
Concentration of the chemical
Temperature
Equipment
Amount of Chemical
To make the test fair I must keep the following the same-:
Diagram.
Method.
To start I will need to set up all my equipment as you can see from my diagram above. (Under the flask you should place you should place your cross.)
I will start by measuring 50cm* of Hydrochloric acid and pour this into the flask. I will then take 50cm* of sodium Thiosulphate. As soon as you pour this into the flask you must start timing.
You should only stop timing when you can no longer see the cross I will repeat each different concentration five times. As I have realised the temperature is a variable I will take the temperature throughout this experiment. I will do this to ensure it stays at a constant temperature, as it will not effect my results.
Safety.
To make my experiment safe I will wear safety and clean up any spills immediately.
Results.
% Concentration Time (secs) 1 2 3 4 5 avg. Reac. Rate
100% 28.09 29.41 28.54 25.63 30.06 28.35 0.035
80% 37.03 30.18 32.25 33.27 34.5 33.44 0.029
60% 38.94 40.38 41.63 45.13 42.06 41.63 0.024
40% 60.61 59.92 62.47 60.31 102.69 69.2 0.014
20% 135.28 129.44131.08134.49 135.93 133.2 0.0075
Accuracy- I know that my results are accurate because all my points are relatively near my line of best fit and there are no anomalous points. I also know my results are accurate, as the overall percentage error is 6.44%.
Below you can see that I have worked this out by using Doubling.
I have chosen 5 different rates of doubling they are -:
10% - 20%
20% - 40%
30% - 60%
40% - 80%
50% - 100%
10% - 20%
10% = 0.0031
20% prediction = 0.062
20% actual = 0.061
% Error = 0.001 x 100 = 1.6%
0.061
20% - 40%
20% = 0.061
40% prediction = 0.122
40% actual = 0.135
% Error = 0.013 x 100 = 9.6%
0.135
30% - 60%
30% = 0.115
60% prediction = 0.23
60% actual = 0.214
% Error = 0.016 x 100 = 7.4%
0.214
40% - 80%
40% = 0.135
80% prediction = 0.27
80% actual = 0.273
% Error = 0.003 x 100 =10.9%
0.2732
50% - 100%
50% = 0.18
100% prediction = 0.36
100% actual = 0.35
% Error = 0.01 x 100 = 2.7%
0.36
Average % error.
2.7% + 7.4% + 10.9% + 9.6% + 1.6% = 32.2% = 6.44%
5
Conclusion.
I have found out that my quantified prediction was correct, as when the concentration doubled so does the rate of reaction.
I have proved this by my percentage error only being 6.44%
This is because when the concentration doubles the amount of particles have also doubled and so the amount of time taken for each particle to collide and react has shortened or halved and so the time taken has also done the same.
Improvements.
If I did the experiment again I could improve it by reacting the two chemicals more times. Currently I have only reacted each concentration five times if I did each one ten times the accuracy would be better. I could also change the percentage of Sodium Thiosulphate by 10% instead of 20%. I could change the concentration of the acid and see what happens.
The final alteration I could make would be to test for temperature instead of concentration.
