The aim of this investigation is to find out and observe how temperature affects the rate of reaction. I am going to investigate the changes caused to the solution of hydrochloric acid and sodium disulphate when the temperature is changed.

Aim:

Prior Knowledge/Research:

The rate of reaction is the speed at which a chemical reaction precedes, expressed in terms of the amount of product formed or the amount of unit’s time taken for a certain reaction to occur (usually in seconds). Thus for the reaction of two compounds (in this case X and Y) that form a product (Z) the equation would be:

X+Y=Z

The rate of reaction can be affected by a number of factors: temperature, concentration, adding a catalyst and surface area. The one that I am going to be investigating and explaining about is Temperature.

Changes in temperature change the kinetic energy of the particles and hence the numbers of successful collisions with enough energy to break existing bonds and make products. For a reaction to take place reagent molecules must collide with each other. When they do so, they must possess enough energy to cause or initiate a reaction.

The two theories that affect temperature and the rate of reaction are the kinetic theory and the collision theory. The kinetic theory clearly states that the positioning and movement of particles in a substance increases if the temperature increases. Therefore, increasing the temperature increases the energy between the particles and makes them move around a lot more and collide more often.

Bringing the reactive sites closer together means that the likelihood of a reaction occurring is increased so in a final research conclusion, increasing the temperature increases the rate of reaction speed.

Prediction:

As I explained earlier, the rate of a chemical reaction is the speed at which it takes place. Temperature is a major factor in this as increasing or decreasing the temperature changes the movement of particles in a substance therefore changing the rate of reaction. When a reaction mixture is heated up, each particle in it acquires more energy and collides more with other particles.

From my prior knowledge and research, I can make the prediction that if you increase the temperature of a particular reaction, you increase the speed at which it takes place. This is simply ...

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Prediction:

From my prior knowledge and research, I can make the prediction that if you increase the temperature of a particular reaction, you increase the speed at which it takes place. This is simply because the particles carry more energy and collide more often where these collisions contain enough energy

Temperature Raised

Particles, when moving faster, collide with greater power.

The reaction therefore becomes faster

Collisions between particles are useless unless they break the energy barrier and this is exactly what increasing the temperature will allow them to do.

Apparatus:

The equipment I need to carry out the work and to obtain my results is:

· Sodium disulphate solution

· Hydrochloric acid

· 250cm conical flask

· -5 C 70 C thermometer

· 10cm /50cm measuring cylinder

· Heatproof mat

· Bunsen burner

· Wire gauze

· Tripod

· Stop clock

Method:

Firstly, I measured 50cm sodium disulphate solution using the conical flask. The appropriate temperature was checked using the thermometer. It was at this point where I carried out the various temperatures.

At the appropriate temperature, 10cm hydrochloric acid was measured using the measuring cylinders and then added to the flask containing the sodium disulphate. I put a bung on straight after it and the bubbles went up the tube. I then recorded my results.

The stop clock was started immediately to make results more accurate and the time in seconds for the amount of gas that was collected. I carried this out from room temperature (R.T) to 70 C. I used the Bunsen burner at each temperature with the heatproof mat on it and the wire gauze.

I repeated each temperature a total of 3 times to make my results accurate and calculated an average by which I compared each temperature with greater ease.

Reliable Results:

To make my results reliable, I am going to be doing each temperature 3 times between the ranges of Room Temperature to 70 C. That’s nine different results altogether for the temperatures and the average that I will make from the three primary results that I record.

Results:

I have decided to record my results in a table with a graph that is on a separate piece of graph paper:

Temperature(C) Amount of gas collected (cm3)

1 2 3

20 C 10.2 12.3 11.5

30 C 18.9 17.4 18.9

40 C 23.6 24.5 26.7

50 C 35.6 35.7 34.2

60 C 45.2 42.9 43.6

70 C 51.2 52.0 49.3

Analysis Of Results:

From my results, I notice that there is a considerable difference in the amount of bubbles from the lower temperatures to the higher temperatures. All of the times are pretty much the same for the three different recording indicating that the experiment was a pretty successful one. There is a decrease of almost 40 bubbles from the starting temperature to the finishing one.

Conclusion

From my results, I have come to the conclusion that if the temperature of a solution is raised, so is the time for the reaction to occur. More bubbles appeared more rapidly as the temperature rose and I think this was due to the increase of energy between the particles and an increase in energy between collisions. At the lower temperatures, the amount of bubbles was less because the particles did not have as much energy as they did at the higher temperatures. At these temperatures the particles are colliding with much more energy.

Linking Prediction To Conclusion

My original prediction was that if you increase the temperature of a reaction, you decrease the time it takes to occur. And, from looking back on my results, I can see that this hypothesis was correct.

Evaluation

I think that this experiment has gone very well for me. My results were of a particularly accurate standard as I did each temperature the reaction was taking place four times and calculated an average from these times. There were no strange results (anomalies) within my results table and I think that this was because of the extreme caution and care that I put into making sure that the experiment was set up correctly with careful measuring of chemicals and substances.

I think that I could have repeated my results more however for the reason that I feel although the experiment was repeated four times, the most accurate results in experiment can only come from constant repeatability which I did not display in my experiment. That said, the time allocated did not allow me to do so and I believe as an improvement of what I could do if I did the experiment again, I would have to say that, with more time, I would repeat the results further for even more accurate and reliable results.

I believe that I could have improved the method by making it more specific. I stated clearly all the various methods I took in setting the experiment up but I could have been more specific to how all the apparatus was used and perhaps why I used the apparatus I did as well.

I believe that I did get a suitable range of results for this experiment. I recorded results from temperatures that ranged from Room Temperature to 80 C and I think that this is a very good range to see how temperature affects the rate of reaction. However, I feel that this also reduces the chance of knowing if anything changes if the temperature reaches a certain point. Perhaps doing the temperature even higher would enhance my results but this is also quite dangerous so I cannot really say that I could have improved the range of my results.

Some other areas in the experiment that I feel I could have improved on were factors like controlling the stopwatch and measuring the amount of sodium disulphate and hydrochloric acid. There is lots of room for human error here. However the inaccuracies due to them were negligible because I paid close attention to these during the experiment.

Overall, this investigation has been a very successful one. I feel my results and analysis have been as accurate and reliable as they could have been under the time allocated. However I feel with extra time, I could have repeated the experiment and made it even more accurate and adapted it to try other variables i.e. concentration or adding a catalyst. These are the ways that I could expand on the original question.