Question

Mr. Samwell Tarly has to learn Chemistry to become a Maester. He is stuck with Kinetics. Will you help him?

(Maester is just Master in their language)

Choose the appropriate definition of rate constant.

• A. The constant which relates rate of reaction to the temperature.
• B. The rate of the reaction when concentration of reactants is equal to one.
• C. The concentration when rate of reaction is equal to $1mol{L}^{-1}se{c}^{-1}$
• D. The constant which is added to the rate equation to make everything equal to one.

Answer 1

The correct option is B The rate of the reaction when concentration of reactants is equal to one.

Let us take a sample equation like
$aA+bB\to cC+dD$

According to the rate law,
$R\propto \left[A{]}^x\right[B{]}^y$


Remember that x and y may not be equal to a and b.

When we remove the proportionality, we add a proportionality constant.
→ $R=k\left[A{]}^x\right[B{]}^y$

Here, if the [A] = 1 and [B] = 1, then R = k

This is the definition of rate constant. It is the rate of the reaction when the concentration of all the reactants is equal to one.