Which equation represents an addition reaction?

June 2018 NY Regents Chemistry Exam

45 Which equation represents an addition reaction?

(1) C3H8 + Cl2→ C3H7Cl +HCl (2) C3H6 + Cl2 → C3H6Cl2 (3) CaCl2 + Na2CO3 → CaCO3 + 2NaCl

(4) CaCO3→ CaO + CO2

Solution: An addition reaction starts with an alkene (formula CnH2n) and reacts with Br2 or Cl2. In choice 2 we can see that we start with an alkene and react with Cl2.

Answer: 2

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