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Regarding rates of reaction

could someone explain these in really easy terms?

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why is the rate of reaction proportional to 1/time

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average rate of reaction = change in concentration / change in time

my book says: "This is only a reasonable assumption if the concentration of a reactant has fallen by less than 10% during the time elapsed".

^^ Why is that the case??

thank you!!

Reply 1

username2434011

That is the case because, when we look for rate of reaction, we usually look for the initial rate of reaction. over the course of the reaction, concentrations of reactants decrease, causing the rate to lower and so, when we average it out, we get a lower rate than the initial. So the rate would be falling significantly if you time for say half the reactants to react, and so you would get a much slower reaction rate than the initial. 10% seems fine as the rat ewon't change as much as others but it is still a tad inaccurate

Reply 2

username2434011

Also, with regards to 1/t. we use the relative times for rate to occur to compare the rate between data points. so as temperature increases, time for reaction decreases, so 1/t increases, so rate of reaction increases. So it gives us a number relative to the other data points to determine rate and also if must be proportional as when 1/t increases, rate will increase proportioanlly.