Question

If we double the concentration of alkyl halides and nucleophile in

2 reaction, what will be the

overall effect on rate of reaction?​

Answer 1

Answer:

Explanation:

he SN2 Mechanism

In the SN2 mechanism, a nucleophile attacks the substrate and the leaving group, L, departs simultaneously. The reaction occurs in one step and is therefore concerted. The substrate and the nucleophile are both present in the transition state for this step. Because two molecules are present in the transition state, the reaction is bimolecular, as indicated by the number 2 in the SN2 symbol. As a result, the reaction rate depends on the concentrations of both the nucleophile and the substrate. If the substrate concentration is doubled, the reaction rate is doubled. Similarly, if the concentration of the nucleophile is doubled, the rate again doubles. This relationship between the rate and the concentration of the reactants exists because the reactants must collide in the rate-determining step for the reaction to occur. The probability that the nucleophile will collide with the substrate increases if the concentration of either or both species is increased.

Let’s consider the SN2 reaction of the hydroxide ion with chloromethane to give methanol and chloride ion. This reaction is shown with the energy diagram in Figure 7.1. In this plot, the transition state, which occurs at the point of highest energy, contains the hydroxide ion and the substrate. As the reaction proceeds through the transition state, a bond between carbon and the hydroxide ion forms and the bond between carbon and chlorine breaks. The rates of reaction for haloalkanes via the SN2 mechanism decrease in the order primary > secondary >> tertiary. This trend is observed because alkyl groups block the approach of the nucleophile and slow the rate of the reaction (Figure 7.2). This crowding of alkyl groups around the reactive carbon atom is ca