How did the discovery of isotopes help to lead to a revised model of atomic structure?
1 answer:
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Answer : The chemical formula of pure substances are different from those of mixtures because all the matter that exists on earth can be classified into two categories namely; pure substances and mixtures.
A pure substance always consists of a single element or compound. Example Oxygen is formed only of oxygen (O) atoms; whereas the table salt which is formed only by sodium chloride (NaCl) molecules is a compound which is made up of pure elements. A pure substance cannot be further divided into its components.
A mixture is made up of different compounds and/or elements. It can be easily separated using any physical method. Example, sand, salt and saw dust mixed together as a mixture. Also, it will not have a definite chemical formula.
Please refer the attachment for better understanding.
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.
