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Investigating The Rate Of Reaction Between Sodium Investigating The Rate Of Reaction Between Sodium Thiosulphate And Hydrochloric Acid Investigating the rate of reaction between Sodium Thiosulphate and Hydrochloric Acid Diagram Aim: We did 4 experiments to find out how the rate of reaction changes with differing concentrations of Sodium Thiosulphate, Hydrochloric Acid and water. As an inert and stable liquid, water was used to alter concentration of Sodium Thiosulphate without changing the end amount of solution. All the atoms in a water molecule have a full outer shell, so they would not react with the other chemicals. Equipment: ? ? ? ? ? Beakers, ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Measuring cylinders Clamp stand and Clamps? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
Black paper tube? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Light probe and Blue box? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Datalogger? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Lamp? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Total of 30 cm 3 H 0, 50 cm 3 Na S O, 12 cm 3 HCl Method: We wanted to change the concentration of Sodium Thiosulphate and Hydrochloric Acid, but without changing the overall quantities. To do this, the Sodium Thiosulphate and water were mixed at different ratios, with always a constant amount of acid.
The table below shows the 4 different experiments, and what each solution composed of. The? Graph? column relates to the graphs taken from the Datalogger for that experiment, which are included at the back of this piece. Sodium The-sulphate (cm 3) Water (cm 3) Hydrochloric Acid (cm 3) Graph number 20 0 3 DPPAS 02 15 5 3 DPPAS 03 10 10 3 DPPAS 04 5 15 3 DPPAS 05? ? ? ? ? ? ? ? ? ? ? ? We did not do the experiment in which 0 cm 3 Sodium Thiosulphate and 20 cm 3 water were used, as there would have been no reaction.
In total, there were always 20 cm 3 of water and Sodium Thiosulphate, with 3 cm 3 Hydrochloric Acid, giving a total solution of 23 cm 3? ? ? ? ? ? ? ? ? ? ? The black tube was put around and below the beaker to help prevent any unwanted light from entering the light probe, as this would have impaired our results. The reason we used a Datalogger and light probe instead of the old? cross? method, is threefold. First, human error.
The cross would not just disappear? it would fade. There would be no specific point at which the cross would disappear, and the results of your experiment would be based entirely on a person? s eyesight. Second, this method will only tell you (albeit inaccurately) when the cross disappeared, i. e.
how long it took for the reaction to get to a certain point of cloudiness. It would not tell you the varying rates of the reaction. You would not be able to tell if the reaction speeded up, slowed down, went steady all the way e. t. c.
Lastly, what would you do if the reaction never got as far as making the cross disappear? Or what if the reaction took a number of hours to get that far? This traditional method is about as accurate as taking the temperature from a beaker of water with your finger. To do the experiment, we set up the apparatus as explained above. We put the various amounts of chemicals into the beaker, and used the Datalogger and blue box to record the first 3 minutes of the experiment, and then used the computer to draw up a graph. The blue box was set to SLOW and 10 k lux.
Prediction: I predict that the rate of reaction will increase (and get more cloudy, more quickly) when the solution of Sodium Thiosulphate and Hydrochloric Acid are strongest, and there is no water. The reason for this is that it will be easier for the Sodium Thiosulphate to react with the Hydrochloric Acid, as they are the only two chemicals in the beaker, and there is not water to hinder the rate of the reaction. There will also be more Sodium Thiosulphate to react with the Hydrochloric Acid, regardless of how much water there is. Results: The graphs from the Datalogger are included in this project. The filename of each graph correspond to the filenames (Dppas) listed in the table above. The table below shows the amount of time that each graph took to level out, i.
e. how long the experiment took to finish. To work out the rate of reaction over the whole reaction (up to the point where the reaction levelled), I divided the light depreciation (k lux) by the time taken (minutes) to give a rate of k lux / min . Light depreciation is k lux at start minus k lux at end of reaction.
Here are the results: Graph Reaction Finished in k lux at start k lux at end k lux dep. /s DPPAS 02 70 s 8. 9 2. 1. 097 DPPAS 03 80 s 8. 9 2. 7. 078 DPPAS 04 100 s 8. 4 3. 2. 052 DPPAS 05 N/A 8. 3 N/A N/A? ? ? ? ? ? ? ? ? ? ? Analysis / Conclusion: Our results show that, as predicted, the more concentrated solutions reacted more quickly than the weaker ones. As the concentration got weaker, the reaction was slower. I would expect the same pattern of you swapped Sodium Thiosulphate and Hydrochloric Acid for two other chemicals, which are not affected by water, but will react with each other. There were a few anomalies at the beginning of two of our graphs, but the end results were all in proportion. The experiment shown in DPPAS 02 twice as concentrated as the experiment in DPPAS 04.
In theory, this means that the light depreciation was twice as much. 0. 052 times two is 0. 104, which is very close to the result we got of 0. 097. This is assuming that the result of 0. 052 was correct. Giving leeway for inaccuracies, this was as good a correlation as we could have expected? only 0. 008 k lux inaccurate. Also, as you can see from the k lux / sec depreciation rate, I was not able to write up figures for the last experiment. This was because, in the time we recorded the experiment for, the chemicals never stopped reacting.
As with most of the graphs we never, for some reason, recorded a full 3 m (all our graphs finished at between 2 m 45 s and 2 m 55 s). This didn? t really matter, as all the other graphs levelled out within the time recorded. But we stopped recording DPPAS 05 before the reaction stopped, and as a result were not able to work out a finishing time, and thus an overall rate of reaction.
For this reason, I did not think it fair to put in the results we got from the partial experiment into the main table above. We can still however work out a rate for the amount of the experiment that we did. Start light of 8. 3, minus finish light of 4. 6 is 3. 7, divided by time, which is 165, equals 0. 022 k lux dep. /s. Assuming this is the rate of reaction throughout the experiment, we could times this number by four (as DPPAS 05 was four times weaker than DPPAS 02), and end up with 0. 088, which is only 0. 009 k lux dep. /s out. So by correlation these three rates of reaction against concentration, we can see that the results are related, and that the experiment worked well. ?
Evaluation: In all, our experiment worked quite well. We did come across a few problems with accuracy though. One of the most significant one was that the Datalogger's are not 100 % accurate, and do not give very detailed readings So when you take results into account, you have to give some leeway for the inaccuracy of the Datalogger. ? ? ? ? ? ? ? ? ? ? ? On DPPAS 05, we had a huge anomaly, of nearly 4 k lux. This appeared about 20 s into our experiment (according to our graph). We have no idea how or why this happened.
My best guess is that somebody knocked the experiment and / or the Datalogger whilst it was recording. ? ? ? ? ? ? ? ? ? ? ? I would do many things to improve the experiment if I did it again in the future. Firstly, I would leave the experiment for a long time (at least an hour) so that all the experiments would finish. Second, I would do the experiment in a darkroom, and make the tube extend upwards as well so that it covered the lamp, and all the light coming out of the lamp would go through the beaker. If I could, I would also use a more expensive and better quality Datalogger that could record the light more precisely and accurately, but this would prove impractical for just one experiment. ? ? ? ? ? ? ? ? ? ? ? One thing I would be hard pushed to overcome would be the light that passes down through the glass sides of the beaker, via TIR.
This is however not that important, as any light entering the light sensor via this route would remain constant.
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Research essay sample on Rate Of Reaction Hydrochloric Acid
