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Postby Theodore_Herring_1A » Tue Mar 05, 2019 9:04 am

How do you figure out the units for k in different ordered reactions?

Neil Hsu 2A
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Joined: Fri Sep 28, 2018 12:16 am

Re: Units

Postby Neil Hsu 2A » Tue Mar 05, 2019 9:12 am

Looking at the rate law, the units for the rate should end up being M/s, so depending on the order of the reaction, the units of k should be different. If you write out the units of each concentration and the rate, you should be able to figure out the units for k. For example, for a first order reaction, rate = k [A] and since rate is M/s and [A] is M, k should be 1/s. Doing this same thing will give you M^-1s^-1 for second order reactions, M^-2s^-1 for third order reactions, and M/s for zeroth order reactions.

Lorena Zhang 4E
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Re: Units

Postby Lorena Zhang 4E » Wed Mar 06, 2019 8:40 pm

Essentially, the final unit for all reaction is M/s or mol/(L*s). Therefore, you can start from the end and make it back to the unit of k based on the orders.

Cole Elsner 2J
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Re: Units

Postby Cole Elsner 2J » Wed Mar 06, 2019 8:51 pm

Your end goal is to have all units b in M/s. With this, you can figure out what the order of the reaction is and adjust k units to reach that end goal units.

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