Rate definition

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Rate definition

Postby sarahtang4B » Mon Mar 11, 2019 8:40 pm

What is the difference of a rate constant and rate of a reaction?

Elisa Bass 4L
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Joined: Fri Sep 28, 2018 12:23 am

Re: Rate definition

Postby Elisa Bass 4L » Mon Mar 11, 2019 8:48 pm

The rate constant is represented by a lowercase k. Being a constant, it does not change if the concentrations of the reactants change; it is constant for the reaction at that temperature. On the other hand, the rate of the reaction is what k times concentrations of reactants equals. In other words, in the equation rate = k[A], the “rate” is the rate of reaction. It CAN change with concentration. This is why when a reaction is at equilibrium, the rates of the forward and reverse reactions (which change as the reaction progresses) are the same, but the rate constants (which are always constant for that temperature) are NOT.

Jennifer Su 2L
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Joined: Wed Nov 21, 2018 12:20 am

Re: Rate definition

Postby Jennifer Su 2L » Mon Mar 11, 2019 9:54 pm

Rate constant is the term "k" itself, and it depends on the temperature, (T), frequency factor (A), and activation energy (Ea).

Rate of reaction depends on both "k" and the concentration of reactants. For example, for a reaction aR --> bP, RATE= (-1/a)*(d[R]/dt)= (1/b)*(d[P]/dt) = k[R]^n, where "n" is the order of the reactant.

Angela Grant 1D
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Joined: Fri Sep 28, 2018 12:25 am

Re: Rate definition

Postby Angela Grant 1D » Mon Mar 11, 2019 10:10 pm

rate of a reaction depends on the rate constant (k) and some other variable (we've been working with concentration)

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