Which of the following will react fastest (i.e., profuce most of the Product in a given time) and which will react at the highest rate?
(a) `1 mol` of `A` and `1 mol` of `B` in a `1-L` vessel.
(b) `2 mol` of `A` and `2 mol` of `B` in a `2-L` vessel.
( c) `0.2 mol` of `A` and `0.2 mol` of `B` in a `0.1-L` vessel.

Explanation

Fastest (b): Since there and more reactants present, there will be more Products profuces per unit time.
Highest rate ( c): The vessel with greatest concentration will experience the greatest change in concentration per unit time. The greatest change in concentration per unit time is in ( c).
In (a), `[A] = [B] = (1 mol)/(1 L) = 1 M`
In (b), `[A] = [B] = (2 mo)/(2 L) = 1 M`
In ( c), `[A] = [B] = (0.2 mol)/(0.1 L) = 2 M`