negative and k

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Jonathan Pai 2I
Posts: 121
Joined: Fri Sep 28, 2018 12:27 am

negative and k

Postby Jonathan Pai 2I » Sat Mar 09, 2019 1:27 pm

A first order problem asks to find k, so we used ln[A]=-kt+ln[A]o, but in the solution ignore the negative k value. I thought k could be negative because dont 1st and 0th order have negative slopes in their graph. Do we ignore the negative or how does this work?

Kyle Golden Dis 2G
Posts: 67
Joined: Fri Sep 28, 2018 12:17 am

Re: negative and k

Postby Kyle Golden Dis 2G » Sat Mar 09, 2019 3:54 pm

The "k" value can never be negative. For a first order reaction, the slope=-k. Since the slope is negative, k is the opposite sign of what ever the slope is.

Cole Doolittle 2K
Posts: 30
Joined: Fri Sep 28, 2018 12:20 am

Re: negative and k

Postby Cole Doolittle 2K » Sat Mar 09, 2019 4:05 pm

K cannot be negative because you can't have a negative concentration

Alysa Rallistan 2G
Posts: 32
Joined: Thu Jan 17, 2019 12:16 am

Re: negative and k

Postby Alysa Rallistan 2G » Mon Mar 11, 2019 11:54 pm

The negative in the equation already accounts for the negative slope however the actual value of the rate constant cannot be negative as seen from its units mol/L/s since time is involved you cannot have negative time

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