n and m

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Olivia Young 1A
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Joined: Fri Sep 28, 2018 12:24 am

n and m

Postby Olivia Young 1A » Wed Mar 06, 2019 10:39 am

I am confused as to the meaning of n and m concerning the overall reaction order. In lecture, we used an examples with NH4+ and NO2-, and we determined that rate 2/rate 1 = 2 = 2.0^m, therefore m is 1. I don't know where the 2.0 value came from, or how to determine n.

megan blatt 2B
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Joined: Fri Sep 28, 2018 12:28 am

Re: n and m

Postby megan blatt 2B » Wed Mar 06, 2019 11:19 am

n and m are the variables used to represent the order of the individual reactants. Essentially, you could use any variables to represent the same thing but n and m are most commonly used. The overall order of the reaction is found by adding all of the orders of the individual reactants, so if there were only two reactants then the overall order would be n+m. The value of 2.0 comes from using the experimental data given in the problem. You set the ratio of the concentrations of two trials in the data raised to the power n (or m or whatever variable you use) equal to the ratio of the rate for each of the two trials. In the example you gave, both ratios were equal to 2 so the value of n would be 1 and the reactant would be first order.

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Joined: Fri Sep 28, 2018 12:27 am

Re: n and m

Postby sonalivij » Wed Mar 06, 2019 2:27 pm

When given an experiment table, you choose the two experiments in which one concentration is the same and one is changing. In this case, the concentration of one of the reactants is double so we divide the rates on one side and set it equal to the concentrations divided by each other, which is 2.0, to the power of m. the value of m is determined by seeing what it needs to be so that both sides are equal.

Esther Lee 4H
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Joined: Fri Sep 28, 2018 12:29 am

Re: n and m

Postby Esther Lee 4H » Thu Mar 07, 2019 10:30 am

The 2.0 is derived from the experimental data. I’m pretty sure it will always be given to us if we need it for hw problems or on a test

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