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Rate Law

Posted: Sun Mar 04, 2018 2:36 pm
by Ryan Fang 1D
Why is the rate law for reactants negative?

Re: Rate Law

Posted: Sun Mar 04, 2018 2:38 pm
by Sean Monji 2B
The rate law shows how the concentration of the reactants are changing over time. If the reactants are being consumed to form products, then the reactants must be decreasing. Therefore, the rate at which the concentration of reactants are changing over time must be negative.

Re: Rate Law

Posted: Sun Mar 04, 2018 2:49 pm
by Rachel Formaker 1E
Rates are always given as positive values.

Since the equation for rate is rate= d[]/dt
and the concentration of reactants is decreasing, simply using the above equation for the rate of consumption of reactants would yield a negative rate.

To correct this and give a positive rate for rate of consumption, we use
rate = - d[reactants]/dt

Re: Rate Law

Posted: Sun Mar 04, 2018 4:02 pm
by 204918982
The concentration of reactants is negative so there needs to be a negative sign to cancel it out and make the rate positive