Addition and Substitution Reactions - UNSOLVED PRACTICE SET

Q7. Define addition reaction. Give one example with a chemical equation.

Q8. Define substitution reaction. Give one example with a chemical equation. 

Q9. Why do saturated hydrocarbons undergo substitution reactions while unsaturated hydrocarbons undergo addition reactions?

Q10. What is hydrogenation? Write the chemical equation for the hydrogenation of ethene. Name the catalyst used.

Q11. Your mother uses vanaspati ghee for making sweets. The ghee is made by hydrogenating vegetable oil. Explain what type of reaction this is and why vegetable oil needs to be converted into ghee. 

Q12. Distinguish between addition and substitution reactions on the basis of:

(a) Type of hydrocarbon involved

(b) Nature of the product formed

Q13. Explain the difference between addition reactions and substitution reactions with suitable examples. Why can unsaturated hydrocarbons undergo addition reactions but saturated hydrocarbons cannot? Illustrate with the reactions of ethene and ethane with bromine.

Q14. Describe the hydrogenation of vegetable oils with a labelled diagram of the apparatus. Why is nickel used as a catalyst? Explain the health implications of consuming hydrogenated fats (trans fats) versus natural vegetable oils.

Q15. In your chemistry lab, you perform two experiments:

Experiment 1: Passing ethene gas through bromine water

Experiment 2: Reacting methane with chlorine in sunlight

(a) What colour change would you observe in Experiment 1? What type of reaction occurs?

(b) What would you observe in Experiment 2? What type of reaction occurs?

(c) Write chemical equations for both reactions.

(d) Why does Experiment 2 require sunlight, while Experiment 1 does not?

Q16. In an addition reaction, 2.8 g of ethene (C₂H₄) reacts completely with hydrogen.

(a) Write the balanced chemical equation.

(b) Calculate the mass of ethane (C₂H₆) produced. (Atomic masses: C = 12, H = 1)

(c) How many molecules of hydrogen are required to react with one molecule of ethene?

Q17. A student carries out the chlorination of methane. In the first step, one hydrogen atom is replaced by chlorine.

(a) Write the chemical equation for the first substitution step.

(b) If 16 g of methane is used, calculate the mass of chloromethane (CH₃Cl) produced. (Atomic masses: C = 12, H = 1, Cl = 35.5)

(c) What would be the product if all four hydrogen atoms are replaced by chlorine?

Q18. A cooking oil company wants to convert 500 kg of unsaturated vegetable oil into saturated vanaspati ghee.

(a) Write the general equation for the hydrogenation reaction.

(b) If the oil contains mainly oleic acid (C₁₇H₃₃COOH), calculate how many kilograms of hydrogen gas would be required to completely saturate 500 kg of oil. (Assume 1 mole of H₂ is needed per mole of oleic acid; Molar mass of oleic acid = 282 g/mol)

(c) Why do health experts recommend limiting the consumption of hydrogenated fats?