How to solve
This method requires that a reaction be run several times. The initial concentrations of the reactants are varied. The reaction rate is measured just after the reactants are mixed. Eliminates the effect of the reverse reaction.
A + 2B 3C + D [A] [B] Initial Rate ?
Rate = k[A] x [B] y Take any two experiments where the [ ] of one species is held constant = k[.240] x [.480] y 2.00 = k[.240] x [.120] y 4.00 = 4 y therefore, y = 1
Now repeat the process, holding the other [ ] constant = k[.240] x [.120] y.500 = k[.120] x [.120] y 4.00 = 2 x therefore, x = 2
Rate = k[A] 2 [B] Determine the value of k with units: 8.00 = k[.240] 2 [.480] 290 L 2 /mol 2 sec = k Determine the initial rate for the last experiment rate = 290[.0140] 2 [1.35] rate =.0767 mol/l sec
For the reaction BrO Br - + 6H + 3Br H 2 O The general form of the Rate Law is Rate = k[BrO 3 - ] n [Br - ] m [H + ] p We use experimental data to determine the values of n, m, and p
Initial concentrations (M) Rate (M/s) BrO 3 - Br - H+H+H+H x x x x x x x x Now we have to see how the rate changes with concentration
x = 1 y = 1 z = 2 Rate Law = k[BrO 3 - ][Br - ][H + ] 2