Prediction:
I predict that the temperature will have an effect on the rate of the reaction. I think that there will be a pattern/trend in my results. I believe that the time for the reaction to occur will steadily decrease as I increase the temperature.
I think this because from my scientific knowledge I know that as the temperature increases, the particles in the liquid have more energy and so move faster and cause more collisions. Some colliding particles just bounce of each other. They don’t bang hard enough to start a reaction. They don’t have enough energy. However, at higher temperatures, the particles are moving faster. They crash together harder. Therefore, more collisions produce a reaction. So, raising the temperature makes particles collide more often in a certain time, and makes it more likely that collision result in a reaction. As there are more, effective collision temperature has a large effect on rates of reaction. If you raise the temperature by 10 degrees Celsius, you roughly double the rate of many reactions.
Equipment
100cm3 Conical Flask
Stopwatch
Hydrochloric Acid
Sodium Thiosulphate
Water
50cm3 Measuring Cylinder
10cm3 Measuring Cylinder
Thermometer
0-110 oC Thermometer
Kettle
Diagram:
Method:
- Set up apparatus
- Record the temperature of sodium Thiosulphate solution
- Pour in the hydrochloric acid into the sodium Thiosulphate solution
- Start the clock
- Stop the clock when the solution becomes milky and the cross is no longer visible
- Record the time taken in seconds
- Boil water in a kettle
- Pour boiling water into a beaker
- Place conical flask with the sodium Thiosulphate solution inside, into the beaker
-
Remove conical flask when temperature is raised to 10o C
- Repeat steps 2-6 using the same volume of sodium thiosulphate solution and hydrochloric acid
- Repeat steps above 3 times
Fair testing:
For this experiment to be a fair test I will make sure that I completely rinse all of my apparatus to make sure that I remove any particles that may have been left from previous experiments. I will not stir or move around the chemicals in any way, as this will prevent any unwanted collisions that may inadvertently speed up the rate of the reaction. Also, I will repeat the experiment for each temperature three times in order to obtain an overall average. I will record the temperature of the liquids at the start and at the end of each attempt to find an average temperature and to see if any faults had occurred in the temperature of the liquid.
Safety:
In my experiment I will carry out everything as safety as possible. I will not run at all as this could lead me to fall or trip, which could end up in me knocking some one over carrying hot materials or chemicals and as a result they could end up spilling them on you and themselves. If any chemicals were to be spilt, it will be cleaned up as quickly as possible and I will be careful not to let it get in contact with my skin because acids are corrosive. Also, wearing goggles is a must because the chemicals are going to be very hot and it could splash or spit out of the flask.
Results:
Analysis:
All results have now been obtained and they seem to be quite good. I also have an average worked out from the three attempts I carried out.
My prediction has been proven. The time for the reaction to occur will steadily decrease as I increase the temperature. The results table and graph shows this.
Evaluation:
Overall, I think that my experiment went quite good. If I could improve on this experiment I would change the plastic measuring cylinders we used to measure out our liquids to glass pipettes. This is because measuring cylinders are mass-produced and so are not 100 % accurate. A glass pipette should have been used as they are hand made and much more accurate. Also glass is clearer than plastic so you can take a reading of the liquids easier and more accurately.
The substances we used were made from stock solutions that were made fresh every lesson therefore the concentration of these substances changed slightly from day to day during the experiment.
The equipment was rinsed with tap water that contains many impurities, which may have contaminated or changed the concentration of the liquids. Distilled water should have been used as it is pure and has no impurities but once again I didn't have the time to keep distilling more and more water just to rinse my equipment.
