Conclusion:
After carrying out this experiment in order to investigate the concentration on a rate of reaction, I have come to the conclusion that concentration does have an effect on the rate of reaction. This is shown in the graph that I have obtained from my results. From the graph, I have obtained these results below in order to prove or disprove my hypothesis.
20/10 = 2 0.0205/0.011 = 1.86
30/15 = 2 0.03/0.0175 = 1.71
The results I have obtained from my graph does not prove my hypothesis to be correct, even though my results are quite close to my hypothesis.
Evaluation:
Possible Errors:
Flask (50cm³ with + 0.3cm³) = + 0.6% error
Measuring cylinder (2 of 100cm³ with + 1cm³ error) = + 2% error
Measuring cylinder (10cm³ with + 0.2cm³) = + 2% error
Stop watch (+ 0.05)
Total percentage error for this experiment was calculated to be = + 5.08%.
- Parallax errors could have occurred while taking reading off the thermometer and measuring cylinders as they were probably not at eye level.
- There could be an error in recording the time as it depends on the eyesight of the person to decide whether or not the cross has disappeared.
- The rate of stirring the contents in the conical flask could have influenced the rate of reaction as it could have increased it.
Possible solutions:
- The solution should be stirred at a constant rate so that the rate or reaction does not get affected by it.
- Use a burette in order to get a more accurate reading of the solution to decrease the percentage error.
- Repeat the experiment more than once in order to average out the results and get a more accurate result.
The Effect of Temperature on the Rate of Reaction
Aim:
To investigate the reaction between sodium thiosulphate and hydrochloric acid and the effect of varying the temperature upon the precipitation of sulphur.
2NaCl(aq) + SO2(g) + S(s) + H2O(l) 2HCl(aq) + Na2S2O3(aq)
Background Theory:
Increasing the Temperature increases reaction rates because of the disproportionately large increase in the number of high energy collisions. It is only these collisions (possessing at least the activation energy for the reaction) which result in a reaction. The temperature measures how much energy each particle has therefore the higher the temperature, the more energy they have causing the particles to travel at a faster speed increasing the amount of collisions, whilst the lower the temperature, the less energy the particles contain causing them to move slower resulting in less collisions. As the temperature rises, the particles would have a higher activation energy. Maxwell – Boltzman’s theory: The shape of the Maxwell – Boltzman’s distribution changes with changing temperature.The graph below shows that at T1, the amount of molecules with the activation energy is less than the number for T2. T2 is a higher temperature than T1, therefore, more molecules will have the activation energy.
Hypothesis:
An increase in temperature will cause an increase in the rate of reaction because the particles have more kinetic energy therefore they move faster. This causes an increase in the collision rate. Therefore as the temperature doubles, the rate of reaction should also double.
Apparatus:
- Conical flask
- Measuring cylinder
- Bunsen burner\
- Gauze
- Tripod
- Thermometer
- Stopwatch
- Cross on a paper.
Chemicals:
- Sodium thiosulphate solution
- Dilute hydrochloric acid.
Method:
As on sheet.
Diagram:
Results:
Conclusion:
After carrying out this experiment in order to investigate the effect of temperature on a rate of reaction, I have come to the conclusion that temperature does have an effect on the rate of reaction. This is shown in the graph that I have obtained from my results. From the graph, I have obtained these results below in order to prove or disprove my hypothesis.
40/20 = 2 0.017/0.0058 = 2.93
60/30 = 2 0.035/0.015 = 2.33
The results I have obtained from my graph does not prove my hypothesis to be correct.
Evaluation:
Possible Errors:
Flask (50cm³ with + 0.3cm³) = + 0.6% error
Measuring cylinder (2 of 100cm³ with + 1cm³ error) = + 2% error
Measuring cylinder (10cm³ with + 0.2cm³) = + 2% error
Stop watch (+ 0.05)
Thermometer (100º with + 1º) = + 1%
Total percentage error for this experiment was calculated to be, + 6.08%.
- Wind from the air-conditioning system could have reduced the temperature.
- Parallax errors could have occurred while taking reading off the thermometer and measuring cylinders as they were probably not at eye level.
- The thermometer absorbed heat from the solution.
Possible solutions:
- Carry out the experiment in an area with no wind currents.
- Try to avoid any parallax errors by taking readings at eye level from measuring cylinders and thermometers.
