· Measuring Cylinder
· Thermometer
· Goggle
· Light sensor
· Clay pipe triangle
· Clamp
· Water baths
Method
- Set up the apparatus as in the diagram.
- Measure out the volumes of the chemicals needed in a measuring cylinder read at eye level.
- Add 20cm3 of distilled water, then 30cm3 of Sodium thiosulphate then 5cm3 of hydrochloric acid and immediately start the clock.
- Record the light level (in lux) displayed on the light sensor at 30 seconds intervals.
- Repeat with Sodium thiosulphate at four other temperatures repeat the whole experiment three times so it's more reliable.
Fair Test
Accuracy
To make my experiment precise I was very accurate measuring the solutions.
I made sure I did the experiment exactly the same way each time I repeated it.
I repeated the experiment three times and used the mean (Average) results.
Safety
To conduct my experiment safely I followed normal laboratory rules, which include:
·The wearing of safety goggles, as things are very unpredictable.
·Standing up to conduct the experiment, therefore reducing the risk of tripping and spilling chemicals.
·Taking care when handling chemicals, particularly Hydrochloric acid and Sodium Thiosulphate because they are irritants.
·Taking care when using glassware to prevent injury.
· Making, sure that coats and bags are all out of the way while doing the experiment.
Results
The results of my table are shown below:
Temperature-13°C- cold
24°C -Room Temperature
Temperature-30°C
Temperature-40°C
Temperature-55°C
Conclusion
I conclude that the higher the temperature the quicker the rate of reaction time will be. I have come to this conclusion because of several reasons. Firstly, my results give conclusive evidence that increasing the temperature increases the speed of the reacting particles and faster particles collide more often than slow ones. The increase in the number of collisions leads to an increase in the rate of reaction. Increasing the temperature also gives the particles more energy so that they collide with more violence. Energetic particles have a better chance of their collisions leading to a reaction. My results support the prediction I made because I said the higher the temperature, the faster the rate of reaction time will be. I believe I was correct and a secondary source states that the reaction time will be faster with a higher temperature because the energy released causes greater collisions and therefore the reaction rate is speeded up. The graph results shows that the slowest reaction rate is the 13°C line, however this rate was illustrated in a straight line. All the other lines are curves. The 55°C is the steepest (and so it is the fastest reaction). The next fastest reaction is 30°C then 40°C and then 24°C. The lines don't end at the same light level although this is what you would expect.
Evaluation
I think that most of the experiment I have done has been fine, with as little anomalous results as possible. However, there are still a few anomalous results. They are ringed on the graph. The result may have turned out anomalous because of basic human error, or maybe because we measured the substances wrong. It may have even been because we did not clean the apparatus properly.
Apart from this, the accuracy of my experiment has been more or less accurate. Although there are a number of ways in which we could have made the results more reliable. For instance, we could have used better measuring equipment, because the apparatus we used was mainly basic equipment.
Another thing we could have done to bring more evidence is to have tried to use the hydrochloric acid as the variable substance, and used the sodium thiosulphate as the constant substance. This would have brought more evidence to support the idea that the higher concentration of a substance, the faster it will react.
