Answer:
(a) Ethyl acetate and hexane, and (c) methanol and methylene chloride.
Explanation:
re-crystallization is a technique used to purify solid compound. Ethyl acetate and hexane are good solvent pair for recrystallization because they are miscible with each other due to their good differences in polarity. ethyl acetate has polarity of 77 while hexane has 68.
water and diethyl ether are not good solvent pair for recrystallization because water and diethyl ether are immiscible. They have very far polarity values. water has 100 while diethyl ether has 35
Answer:
The carbocation intermediate reacts with a nucleophile to form the addition product.
Explanation:
The reaction of benzene with an electrophile is an electrophillic substitution reaction. Here the electrophile replaces hydrogen. There is no formation of carbocation as intermediate in the reaction. Infact there is transition state where the electorphile attacks on benzene ring and at the same time the hydrogen gets removed from the benzene. So a transition carbocation is formed.
The general mechanism is shown in the figure.
i) Attack of the electrophile on the benzene (which is the nucleophile)
ii) The carbocation intermediate loses a proton from the carbon bonded to the electrophile.
iii) the carbocation formation is the rate determining step.
iv) There is no formation of addition product.
Thus the wrong statement is
The carbocation intermediate reacts with a nucleophile to form the addition product.
Higher temperature = higher energy. In water it is a liquid as the particles have more energy so vibrate and are further away from each other.
It is easiest to tell if a solution is saturated if there is residue on the bottom. If it crystallized, the solution is saturated. If it is a supersaturated solution, there will not be crystallization unless more of the solute is added, at which point all of it will crystallize.