In: Chemistry
Determine the rate law for the reaction A+ B → C given the following initial rate data.
[A], M [ B], M ∆[C]/∆t (mol/L•s)
0.10 0.20 40.
0.20 0.20 80.
0.10 0.10 40.
1. Observe experiments 1 and 2. The initial concentration of A doubles while the initial concentration of B remains constant. As a result, the rate also doubles from 40 mol/L s to 80 mol/L.s. Therefore the reaction is first order with respect to A.
2. Now examine experiments 1 and 3. The initial concentration of A remains constant while concentration of B is doubled from exp. 3 to 1. The result of this change is that the rate of the reaction does not change it remains same. We conclude that B is not a part of the rate law expression.
Therefore, the rate law for the above reaction is:
rate = k [A]