## determining order

$\frac{d[R]}{dt}=-k[R]^{2}; \frac{1}{[R]}=kt + \frac{1}{[R]_{0}}; t_{\frac{1}{2}}=\frac{1}{k[R]_{0}}$

lauraxie2e
Posts: 108
Joined: Fri Aug 09, 2019 12:17 am

### determining order

In word problems would they usually tell us the order so we would know what equation to use? If not, how would we determine what equation to use?

McKenna_4A
Posts: 115
Joined: Sat Aug 24, 2019 12:18 am

### Re: determining order

Plot the initial concentrations as 1/c, ln(c), and just c. Whichever one gives a linear plot is the correct order.

Sanjana Munagala_1j
Posts: 103
Joined: Sat Aug 24, 2019 12:17 am
Been upvoted: 1 time

### Re: determining order

You could be able to determine the order of a reaction or the order in respect to a certain reactant by experimental data. In this case you would see how the concentration changes in relation to the change in rate. Another way to find the order of the reaction is through the units of K, the rate constant, in which the units remain the same for the same order.

Hope that helps!

vibha gurunathan 1h
Posts: 51
Joined: Mon Oct 07, 2019 12:15 am

### Re: determining order

You determine the order from experimental data - the method usually depends on the information given in the problem.

205405339
Posts: 77
Joined: Thu Jul 11, 2019 12:16 am

### Re: determining order

When given experimental data, input the given values into time vs ln[a] (first order), time vs 1/[a] (second order), and time vs [a] (zero order) and look for the graph with the linear graph. this determines the order of that particular reactant.

005162520
Posts: 101
Joined: Tue Sep 24, 2019 12:17 am

### Re: determining order

Can we also determine order based on it stoichiometric coefficient ?

Lindsey Chheng 1E
Posts: 110
Joined: Fri Aug 30, 2019 12:16 am

### Re: determining order

005162520 wrote:Can we also determine order based on it stoichiometric coefficient ?

yes i think you can!

alex_4l
Posts: 109
Joined: Thu Sep 26, 2019 12:18 am

### Re: determining order

Sanjana Munagala_1j wrote:You could be able to determine the order of a reaction or the order in respect to a certain reactant by experimental data. In this case you would see how the concentration changes in relation to the change in rate. Another way to find the order of the reaction is through the units of K, the rate constant, in which the units remain the same for the same order.

Hope that helps!

This helped me so much thank you!

Posts: 102
Joined: Tue Oct 02, 2018 12:16 am

### Re: determining order

You can use experimental data by plotting the data using the formulas observed in class and try to achieve a linear plot. If they give you a list of intermediate steps, the slow step will be the rate law which will give indication to the order.

Altamash Mahsud 1I
Posts: 50
Joined: Fri Aug 09, 2019 12:16 am

### Re: determining order

If the order is not told to you in the problem, then there are a few ways of figuring it out. One way could be through experimental data, in which you would see how the rates would change in respect to a reactant concentration changing, then compare the different experiments to find the order with respect to each reactant, then add all those orders up to get the overall order of reaction. You could also find the overall order of the reaction by looking at the units of k, the rate constant.