What happens to intermediates when deriving the overall reaction from the mechanism?

What happens to intermediates when deriving the overall reaction from the mechanism?

• A. They cancel out and do not appear in the overall equation
• B. They are added to the final equation as products
• C. They are the only species in the rate law
• D. They are carried through to the products

Answer: (A)

Intermediates are species formed in one step and consumed in a later step. When you add all steps in a mechanism to get the overall reaction, these intermediates appear as products in one step and reactants in another. Because you’re summing the steps, those species cancel out, leaving only the actual reactants and final products in the net equation. For example, if a mechanism has A → B and B → C, B is an intermediate. Adding the steps gives A → B and B → C, which combine to A → C after canceling B.

Intermediates are species formed in one step and consumed in a later step. When you add all steps in a mechanism to get the overall reaction, these intermediates appear as products in one step and reactants in another. Because you’re summing the steps, those species cancel out, leaving only the actual reactants and final products in the net equation.

For example, if a mechanism has A → B and B → C, B is an intermediate. Adding the steps gives A → B and B → C, which combine to A → C after canceling B.