## Negative Signs [ENDORSED]

$aR \to bP, Rate = -\frac{1}{a} \frac{d[R]}{dt} = \frac{1}{b}\frac{d[P]}{dt}$

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donnanguyen1d
Posts: 64
Joined: Fri Sep 29, 2017 7:04 am

### Negative Signs

Whenever we have to find a rate, is it always going to be positive by using the absolute value of change in [R]? When is it negative?

Britney Alvey 1B
Posts: 31
Joined: Fri Jun 23, 2017 11:39 am

### Re: Negative Signs

You always want to work with positive reaction rates.

Nina Gautam 1K
Posts: 52
Joined: Fri Sep 29, 2017 7:04 am

### Re: Negative Signs

The reaction rate should always be positive because even if a species is reducing in concentration, which is negative, we are describing the speed at which it is changing with respect to time

Amanda Wu 2C
Posts: 31
Joined: Sat Jul 22, 2017 3:00 am

### Re: Negative Signs

It is customary that the unique reaction rate is positive, because you're describing the rate at which the reaction proceeds as time progresses. Thus, you negate the reactant rate (d[R]/dt) (and if needed, divide by the stoichiometric coefficient of R) to get the positive unique reaction rate.

Jessica Wakefield 1H
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Joined: Thu Jul 27, 2017 3:00 am

### Re: Negative Signs

yes because your reaction rate is in reference to speed so the value should be positive

Shanmitha Arun 1L
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Been upvoted: 1 time

### Re: Negative Signs

We want to work with positive numbers so you should make sure the rate is positive.

Adrian Lim 1G
Posts: 88
Joined: Fri Sep 29, 2017 7:03 am

### Re: Negative Signs  [ENDORSED]

We usually want the rate to be a positive number because it might seem unusual for a rate to be a negative number. Thus, when we calculate the rate of a reactant, we usually add the negative sign in front of the change of concentration over change in time. This is because the change in concentration is probably negative for reactants, so by adding another negative in front of a negative, we would make this rate positive.

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