Obviously, you could then repeat the process by changing something else - the concentration of a different substance, or the temperature, for example.Tags: Power Corrupts People EssayDo My Assignments UkAp Biology HomeworkProduct Design Research PaperDiegos Mexican Food CantinaEffects Teenage Pregnancy EssayUniversity Of Mississippi ThesisMusic Dissertation Topics
The maths of this might not be familiar to you, but you may find that you are asked to do this as a part of a practical exam or practical exercise.
If it is an exam, you would probably be given help as to how to go about it.
This could be a reaction between a metal and an acid, for example, or the catalytic decomposition of hydrogen peroxide.
If you plotted the volume of gas given off against time, you would probably get the first graph below.
Measuring the slope of a straight line is very easy. Now suppose you did the experiment again with a different (lower) concentration of the reagent.
Rates Of Reaction Between Sodium Thiosulphate And Hydrochloric Acid Coursework Why Did Ww1 Happen Essay
Again, we will measure the time taken for the same volume of gas to be given off, and so we are still just looking at the very beginning of the reaction: The initial rates (in terms of volume of gas produced per second) are: of gas, you just collected the gas up to a mark which you had made on the side of a test tube. If you are simply wanting to compare initial rates, then it doesn't matter.Since this is the part of the reaction you are most interested in, introducing errors here would be stupid!You have to find a way of adding the catalyst to the hydrogen peroxide solution without changing the volume of gas collected.You can then plot 1/t as a measure of rate against the varying concentrations of the reactant you are investigating.If the reaction is first order with respect to that substance, then you would get a straight line.This is repeated for a range of concentrations of the substance you are interested in.You would need to cover a reasonably wide range of concentrations, taking perhaps 5 or so different concentrations varying from the original one down to half of it or less.Or you could measure the time taken for some dramatic colour change to occur. You then change the concentration of one of the components of the reaction, keeping everything else constant - the concentrations of other reactants, the total volume of the solution and the temperature and so on.Then you find the time taken for the same event to take place with that new concentration.This page is an introduction to some of the experimental methods that can be used in school labs to find orders of reaction. How initial rate experiments work An outline of the experiments The simplest initial rate experiments involve measuring the time taken for some easily recognisable event to happen very early on in a reaction.There are two fundamentally different approaches to this - you can either investigate what happens to the initial rate of the reaction as you change concentrations, or you can follow a particular reaction all the way through, and process the results from that single reaction. This could include the time taken for, say, 5 cm of gas to be produced.