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### Negative Signs

Posted: Wed Feb 28, 2018 5:24 pm
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?

### Re: Negative Signs

Posted: Wed Feb 28, 2018 5:47 pm
You always want to work with positive reaction rates.

### Re: Negative Signs

Posted: Wed Feb 28, 2018 5:55 pm
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

### Re: Negative Signs

Posted: Wed Feb 28, 2018 9:21 pm
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.

### Re: Negative Signs

Posted: Thu Mar 01, 2018 12:18 pm
yes because your reaction rate is in reference to speed so the value should be positive

### Re: Negative Signs

Posted: Thu Mar 01, 2018 1:25 pm
We want to work with positive numbers so you should make sure the rate is positive.

### Re: Negative Signs  [ENDORSED]

Posted: Thu Mar 01, 2018 11:58 pm
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.