2A + B2 + C --> A2B + BC
Run # Initial Rate (M-1s-1) (A)o (B)o
(C)o
1 1.6 x 106 1.2 M 1. x 10-2 M 1.0 M
2 1.6 x 106 2.4 M 1. x 10-2 M 1.0 M
3 3.2 x 106 1.2 M 2. x 10-2 M 1.0 M
4 6.4 x 106 1.2 M 1. x 10-2 M 2.0 M
What would be the rate-law expression of the reaction above?
1 and 2; C is same, B is same, A doubles and rate stays same; therefore, the reaction is zero order for A.
2 and 3. C is same. A doesn't matter since it is zero order. B doubles and rate doubles; therefore, the reaction is 1st order with in B.
1 and 4. A same. B same. C doubles while rate quadruples; therefore, the reaction is 2nd order in C.
rate = k(A)^o*B)^1(C)^2
Use any trial, substitute the values for concn of A, B, and C and solve for k.
To determine the rate-law expression for the given reaction, we need to analyze the data provided and observe how the initial rate varies with the initial concentrations of the reactants.
The initial rate of the reaction is given for each run. By comparing the initial rates for different runs while keeping one reactant concentration constant, we can determine the order of the reaction with respect to that reactant.
From the data provided, we can see that the initial rate remains constant (1.6 x 10^6 M^-1s^-1) for runs 1 and 2, where the concentration of reactant B (1 x 10^-2 M) is constant, but the concentration of reactant A changes. This suggests that the reaction is not dependent on the concentration of reactant A.
Similarly, the initial rate remains constant (1.6 x 10^6 M^-1s^-1) for runs 1 and 4, where the concentration of reactant A (1.2 M) is constant, but the concentration of reactant B changes. This also suggests that the reaction is not dependent on the concentration of reactant B.
However, when comparing runs 1 and 3, where the concentration of reactant C changes while keeping the concentrations of reactants A and B constant, we observe that the initial rate doubles from 1.6 x 10^6 M^-1s^-1 to 3.2 x 10^6 M^-1s^-1. This indicates that the initial rate is directly proportional to the concentration of reactant C.
Based on the analysis above, we can conclude that the rate-law expression for the given reaction is:
Rate = k[C]
where k is the rate constant and [C] represents the concentration of reactant C.
Therefore, the rate-law expression for the reaction is: Rate = k[C].