Finding order of reaction

[Chem_Mod]

You said that to determine the order of the reaction experimental techniques would have to be used. Does this entail simply plotting concentration versus time and then observing the changes in the tangents to the curve, and then using these changes to derive some sort of expression?

[Chem_Mod]

There are different ways of determining the order of the reaction. If provided a chart with experiments, you would have to use that to find the order of the reaction. If given a plot, you can find the order of the reaction by looking at the axis labels and the slopes.

[Claudia_Danysh_2B]

Yes, I think the best way to do this is to remember that you're looking for a line when you graph time vs. [A], ln[A], or 1/[A]!

[Edgar Velazquez 2K]

I think that the more common way is to use a table of provided initial rate and concentration values. That way you will be able to see how changes in concentration for each different molecule affect the rate of the reaction. You then use that information to determine the orders.

[Arya Adibi 1K]

This could be one method of determining the order of a reaction. However, you have to be careful when analyzing the plot of concentration vs. time.

Example Reaction: A --> P
Plot of [A] vs. Time:

If the plot is linear with a negative slope, that would imply a zero order
If the plot is decreasing curved/exponential, it could either be first or second order. More analysis of concentrations at different points of time would have to be done to distinguish between first and second order.

[Amanda Dankberg 1B]

There are multiple ways of finding the order of reaction, n. One way is as you mentioned of plotting concentration against time. if you plot concentration against time directly and it forms a straight line, it is a 0 order reaction. If it is not a straight line, you can try plotting the ln of the concentrations against time and if that is a straight line then it is a first order reaction. If that still does not result in a straight line you can plot 1/the concentrations against time and if that is a straight line it is a second-order reaction. If a chart of experimental data is shown, however, you can simply compare the increase of concentrations to the increase of the rates. If they increase at the same rate, it is a first order reaction and if the rate increases at double the rate of the concentration then it is a second order reaction.