We’re asked to determine the overall rate constant K for the given two steps mechanism.

When a **reaction mechanism **is given, the **rate law will depend on reactants and products in the slow step**.

▪Rate law only *involves the reactants*

▪ The *coefficients *of the reactants in the slow step are the *order* of the reaction with respect to that reactant

▪ Rate Law has a general form of:

$\overline{){\mathbf{Rate}}{\mathbf{}}{\mathbf{Law}}{\mathbf{=}}{\mathbf{k}}{\left[\mathbf{X}\right]}^{{\mathbf{a}}}{\left[\mathbf{Y}\right]}^{{\mathbf{b}}}}$

Where

k = rate constant

X & Y = reactants

a & b = reactant orders

▪ The equilibrium constant has a general form of:

$\overline{){{\mathbf{K}}}_{{\mathbf{r}}}{\mathbf{=}}\frac{\mathbf{p}\mathbf{r}\mathbf{o}\mathbf{d}\mathbf{u}\mathbf{c}\mathbf{t}\mathbf{s}}{\mathbf{r}\mathbf{e}\mathbf{a}\mathbf{c}\mathbf{t}\mathbf{a}\mathbf{n}\mathbf{t}\mathbf{s}}}$

What is the rate law for the following mechanism in terms of the overall rate constant k?

Step 1: A + B ↔ C (fast)

Step 2: B + C → D (slow)

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Reaction Mechanism concept. If you need more Reaction Mechanism practice, you can also practice Reaction Mechanism practice problems.