The effect concentration of hydrochloric acid has on the rate of reaction -- A* - page 5
Keywords: Rate of reaction hydrochloric acid sodium thiosulphate concentration
By georgie1 on 31/12/2009
Level: GCSE Key Stage 4 (Years 10-11)
Page Number: 5 of 8 pages: 1 2 3 4 5 6 7 8
and therefore did not have to repeat any of my measurement. Upon looking at my graph, I can see that my error bars are usually of consistent range, but I can see that the error bar is larger for 1.0M, which could be interpreted as an anomaly. However, because the lowest value result [that I have used for the lower boundary] is not vastly different to the other two, I do not believe that it is. My error bars could be made more accurate if I was to use standard deviation and calculate this using my results. I would be able to see how spread out my results were for each concentration within each range. However, this would require more than 10 [approx.] results, which was not possible in the time that I was given to complete the experiment.
The experiment may have suffered limitations involving the lighting of the room, which could affect the visibility of the card marked with an ‘X’ underneath the conical flask. I do not think that this will have mattered too much because all of the experiments were completed in the same place every time. However, because I was close to a window, the sunlight may have affected the visibility, which could have caused a slight error in the results.
Because my line of best fit is not straight, I am instantly aware that the rate of reaction is not directly proportional to the concentration of the hydrochloric acid. My curve follows a relatively straight line until the concentration is of 0.6M, when the rate of reaction does not increase as rapidly. [From 0.0M – 0.6M, the rate of reaction increases by 2.36, yet from 0.6M – 1.0M, the rate of reaction only increases by 0.34]. However, because the rate of reaction does continue to increase as the concentration increases, between 0.6M and 1.0M, I know that there is definitely a correlation. I believe that if I was to continue increasing the concentration of the hydrochloric acid, for example to 2.0M, then the rate of reaction would finally reach an optimum rate, where it could not react any faster.
The Collision Theory states: “For a reaction to occur the reactant particles must collide. Only a certain fraction of the total collisions cause chemical change; these are called "successful collisions"¹. The successful collisions have sufficient energy at the moment of impact to break the existing bonds
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