You are staying the reaction A2 (g)+B2 (g)=2AB (g)
To determine its rate law .Assuming that you have a valid experimental procedure for obtaining (A2)&
(B2) at various times, explain how you determine (a)the initial, (b) the reaction order, & (c) the rate constant?
To determine the rate law for the reaction A2 (g) + B2 (g) = 2AB (g), you need to follow these steps:
(a) Determining the Initial Rate:
1. Set up the experimental procedure: You will need to vary the initial concentrations of A2 and B2 while keeping the other factors constant, such as temperature, pressure, and the presence of any catalysts.
2. Choose several experiments: Select different initial concentrations of A2 and B2 and measure the rate of the reaction at each set of concentrations. It's important to include experiments with varying concentrations of both reactants.
3. Calculate the initial rate: Determine the rate of the reaction by dividing the change in concentration of AB by the corresponding change in time. The initial rate is the rate measured at the beginning of the reaction when the reactant concentrations are at their initial values.
(b) Determining the Reaction Order:
1. Compare rate ratios: Once you have obtained the initial rates for different experiments, compare their ratios. Start by comparing the ratios of the initial rates for two experiments where only the concentration of A2 changes while the concentration of B2 remains constant (and vice versa). You are looking to see how changes in the concentration of each reactant affect the rate independently.
2. Determine the reaction order: If, for example, doubling the concentration of A2 results in a doubling of the rate while keeping B2 constant, the reaction order with respect to A2 is 1 (first order). Repeat this process for B2 and determine its order. The overall reaction order is the sum of the individual orders.
(c) Determining the Rate Constant:
1. Select one experiment: Choose one experiment where the initial concentrations of both reactants are known, and the initial rate is determined.
2. Use the rate law equation: Now that you know the reaction order for each reactant, use the rate law equation, which has the general form rate = k[A2]^m[B2]^n, where k is the rate constant.
3. Substitute the known values: Plug the known values from your chosen experiment into the rate law equation. This includes the initial concentrations of A2 and B2, the initial rate, and the reaction orders determined earlier.
4. Solve for the rate constant: Rearrange the rate law equation to solve for the rate constant (k). Once you have substituted the known values, you can solve for k.
By following these steps, you should be able to determine the initial rate, reaction order, and rate constant for the given reaction.