Negative 1/a


Moderators: Chem_Mod, Chem_Admin

Jack Papciak 2F
Posts: 31
Joined: Fri Sep 29, 2017 7:06 am

Negative 1/a

Postby Jack Papciak 2F » Tue Feb 27, 2018 8:53 pm

Why is there a "-" in -1/a in the differential rate law?

Tatiana Hage 2E
Posts: 51
Joined: Thu Jul 27, 2017 3:00 am
Been upvoted: 2 times

Re: Negative 1/a

Postby Tatiana Hage 2E » Tue Feb 27, 2018 9:17 pm

There is a negative sign because the concentration of the reactant decreases during the reaction.

Nicole 1F
Posts: 31
Joined: Fri Sep 29, 2017 7:05 am

Re: Negative 1/a

Postby Nicole 1F » Tue Feb 27, 2018 11:47 pm

In addition, the rate needs to be positive in the end.

Nisarg Shah 1C
Posts: 54
Joined: Sat Jul 22, 2017 3:00 am

Re: Negative 1/a

Postby Nisarg Shah 1C » Wed Feb 28, 2018 9:43 am

Because the reactant is being consumed, the overall concentration of the reactant is decreasing so there is a negative rate of change. However, if the question asked at what rate was A being consumed, then it will be a positive answer. Just be careful about how the question is worded!

Rachel Lu_dis1H
Posts: 66
Joined: Fri Sep 29, 2017 7:06 am
Been upvoted: 1 time

Re: Negative 1/a

Postby Rachel Lu_dis1H » Wed Feb 28, 2018 12:07 pm

Since products is decreasing, the slope will be negative when you take the tangent to the curve. (that means that the slope of the products is positive because products is increasing)

Cristina Sarmiento 1E
Posts: 52
Joined: Wed Nov 16, 2016 3:02 am

Re: Negative 1/a

Postby Cristina Sarmiento 1E » Wed Feb 28, 2018 4:32 pm

Nisarg Shah 1C wrote:Because the reactant is being consumed, the overall concentration of the reactant is decreasing so there is a negative rate of change. However, if the question asked at what rate was A being consumed, then it will be a positive answer. Just be careful about how the question is worded!


Can you please further explain as to why the rate would be a positive answer if the question was worded differently?

Nisarg Shah 1C
Posts: 54
Joined: Sat Jul 22, 2017 3:00 am

Re: Negative 1/a

Postby Nisarg Shah 1C » Fri Mar 16, 2018 8:43 pm

For example, if the question asked "what is the rate of decomposition of reactant A" the rate would be positive, even though the concentration of A is decreasing.

Michael Downs 1L
Posts: 29
Joined: Thu Jul 13, 2017 3:00 am

Re: Negative 1/a

Postby Michael Downs 1L » Fri Mar 16, 2018 8:50 pm

Cristina Sarmiento 1E wrote:
Nisarg Shah 1C wrote:Because the reactant is being consumed, the overall concentration of the reactant is decreasing so there is a negative rate of change. However, if the question asked at what rate was A being consumed, then it will be a positive answer. Just be careful about how the question is worded!


Can you please further explain as to why the rate would be a positive answer if the question was worded differently?


Since the word consumed is being used, then the negative rate of change is already being implied so the answer shouldn't have another negative.

Mitch Walters
Posts: 45
Joined: Fri Sep 29, 2017 7:07 am

Re: Negative 1/a

Postby Mitch Walters » Fri Mar 16, 2018 8:58 pm

Concentration of reactants decreases.


Return to “General Rate Laws”

Who is online

Users browsing this forum: No registered users and 2 guests