Question

Help greatly appreciated!!

A student ran two separate substitution reactions, Reaction A and Reaction B, in lab that utilized an alkyl halide and a nucleophile. However, he did not know if the reactions proceeded through an S_N1 or S_N2 mechanism. To determine the mechanism for both reactions, the student increased the concentration of the nucleophile in Reactions A and B. The rate of reaction for Reaction A increased. The rate of reaction for Reaction B remained the same.

(a) Which reaction is the S_N1 reaction? (1 pt)

(b) Which reaction is the S_N2 reaction? (1 pt)

(c) Explain both of your choices. (4 pts)