Question

The rate of ${E_1}$ reaction depends upon:
A. The concentration of substrate.
B. The concentration of the nucleophile.
C. The concentration of substrate as well as nucleophile.
D. Neither the concentration of substrate nor of nucleophile.

Answer 1

${E_1}$ is a type of elimination reaction. ${E_1}$ stands for unimolecular elimination reaction where subscript 1 denotes $uni$ meaning one. The ${E_1}$ reaction is a two-step unimolecular process which goes through one intermediate state and two transition states.

Complete step by step answer:
The elimination reaction can be broadly classified as ${E_1}$ reaction meaning unimolecular elimination and ${E_2}$ reaction meaning bimolecular elimination.
${E_1}$ reaction is a two-step elimination process; ionization and deprotonation. The ionization step is the slowest and thus being the slowest step is the rate determining. The steps of ${E_1}$ reaction can be depicted in the following figure:

The rate of a given reaction at a given temperature may depend on the concentration of one or more reactants and products. The representation of the rate of reaction in terms of concentration of the reactants is known as rate law.
For the ${E_1}$ reaction first-order kinetics is followed. It can be represented as follows:
$Rate = K[Substrate]$, where $K$ is the proportionality constant known as the rate constant and $[Substrate]$ denotes the concentration of the substrate.
The above expression is called the rate expression
The reaction in which the rate of the reaction is proportional to the first power of the
concentration of the reactant is said to follow first-order kinetics.
From the above rate expression, we can say that the rate of ${E_1}$ reaction is affected by only the concentration of the substrate.

So, the correct answer is (A). The rate of ${E_1}$ reaction depends upon the concentration of the substrate.

Note: ${E_1}$ reaction consists of two steps: the first is the ionization while the second step is the deproteinization process.
The ionization step is the slow of the two steps.
The slowest step of the reaction determines the rate of the reaction.
The ionization step results in the production of carb-anion denoted by ${C^ + }$