Low Temperature High Temperature
The reaction between Hydrochloric Acid and Sodium Thiosulphate is:
Na2S2O3 + 2HCl → 2NaCl + SO2 + H2O + S
As you can observe; this equation is already balanced; there is no need to balance it. The reason an equation needs to be balanced is to see how many of each atoms/molecules are used in a single reaction.
In this investigation; we wish to find out whether the temperature of the reactants affects the reaction rate; hence this coursework is called “Rates Of Reaction”.
When reactants temperature is lower; there are fewer particles that are moving as hard or as fast as they would be moving in a higher temperature concentration. Because at lower temperatures not much is taking place at the atomic and molecular level; the reaction takes place at a slower rate as opposed to a concentration with a higher temperature.
Apparatus:
- Beaker
- Bunsen burner
- Conical flask
- 1 x 100cm flask
- Heat-proof mat
- 2 x 25cm measure cylinder
- Paper with “X” mark on it
- Stop watch
- Test tubes
- Test tube rack
- Thermometer
- Tongs
- Tripod
- 150 ml of water
- Wire gauze
Fair Testing Procedures:
To ensure we have accurate and reliable results; I will be having these procedures undertaken to ensure a fair testing environment.
- The same piece of paper with the “X” mark will be used throughout the experiment.
- The reactants should be in a constant concentration throughout the experiment; as a higher concentration will yield different results.
- Timing should be initiated as soon as the entire measuring cylinders are emptied into the flask; this way we will only start the procedure as soon as the all the preliminary steps are completed; such as emptying all the contents of the beakers.
- Ensure the flask/beaker are both free from contamination. This means that other substances are not present in the apparatus prior to the experiment. This way we will gain the purest results from the chemicals; not the results of the contaminants as well!
- There should only be one person assigned the task of looking at the “X” mark on the paper and waiting to see if it has disappeared or not; this is because different person have different depths of perception.
- Use an electrical means of timing. For this experiment a stopwatch will be used.
- The reactants should be kept in a constant volume to ensure that the results will be the same in that aspect; has a higher/lower volume will give incorrect results.
- Get results twice and if within similar thresholds work out average.
Conclusion:
By looking at my results I can say that my predictions were correct. This is because the higher the temperature was; the faster the rate of reaction would become. This can be observed by looking at the reaction times for a time then observing one for a higher temperature. For example the times for 20c are much more than the times for 50c. This is because when the reactant is heated; its atoms are moving randomly harder and faster; as opposed to another reactant at a lower temperature. Because of this there are more collisions taking place; and because of the heat they are harder; so even more of the collisions meet the minimum activation energy; hence even more reactions are taking place in the mixture.
It is easy to see that the temperature definitely affects the reaction; as this can be seen on my graph. The line of best fit is a definite upwards curve; showing this relationship.
Evaluation:
I think that the results obtained from this experiment were reliable enough to prove my prediction was correct. My results did not go up in steady increments; they were more of a curve; which shows me that there is some other rule that determines this. The reason I think this is not an error is because it is a curve; not just one anomalous result. If I was given more time then I would have repeated this experiment.
If I had any anomalies sticking out then I would first repeat that section of the experiment then I would try and find out why it happened to further my learning.
Despite my results were not as good as they could have been I think they were enough to show that temperature does indeed affect the rate of reaction.
I can also carry out a further investigation to find out whether concentration effects the rate of reaction:
Aim:
To find out whether the concentration of the reactants affects the rate of reaction.
Prediction:
I am predicting that a reaction with a higher concentration of reactants will react much quicker compared to a reaction where there is a lower concentration of reactants.
Hypothesis
The concentration of the reactants determine how much of the particles are there to collide; hence making the reaction take place quicker. A higher concentration results in more particles moving around hence the probability of a successful reaction is much higher.
High Concentration Low Concentration
Method: