## Rate definition

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

sarahtang4B
Posts: 132
Joined: Fri Sep 28, 2018 12:27 am

### Rate definition

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

Elisa Bass 4L
Posts: 61
Joined: Fri Sep 28, 2018 12:23 am

### Re: Rate definition

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
Posts: 47
Joined: Wed Nov 21, 2018 12:20 am

### Re: Rate definition

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
Posts: 67
Joined: Fri Sep 28, 2018 12:25 am

### Re: Rate definition

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