Question 1: Define an alkene in terms of its carbon-carbon bond structure.

Answer: An alkene is a hydrocarbon containing at least one carbon-carbon double bond.

Question 2: Explain why alkenes are generally more reactive than alkanes.

Answer: Because of the presence of the carbon-carbon double bond, which contains a π-bond that is more reactive than single bonds.

Question 1: Describe the mechanism of the addition of hydrogen halides (HX) to alkenes.

Answer: The mechanism involves electrophilic addition where the double bond reacts with HX, forming a carbocation intermediate, followed by the attachment of the halide ion to produce an alkyl halide.

Question 2: What are the conditions required for the catalytic hydrogenation of alkenes?

Answer: Presence of a metal catalyst such as platinum, palladium, or nickel, and high temperature and pressure.

Question 3: Multiple Choice: Which of the following is a product of the reaction between ethene and bromine water? Options: A) Ethanol B) Bromoethane C) 1,2-Dibromoethane D) Ethene oxide

Answer:

Question 4: Fill in the blank: The addition of bromine water to an alkene results in the formation of a _______ compound, which causes the solution to lose its original colour.

Answer: brominated

Question 1: Describe a basic experimental setup to test whether a hydrocarbon is an alkene or an alkane.

Answer: React the sample with bromine water and observe for decolourisation; alkenes will decolourise bromine water due to addition across the double bond, while alkanes will not.

Question 2: Identify two safety precautions that should be taken during the addition of halogens to alkenes in the laboratory.

Answer: Work in a well-ventilated area or fume cupboard; wear appropriate eye protection and gloves to prevent skin and eye contact.

Question 1: A sample of ethene reacts with hydrogen chloride (HCl) to form chloroethane. Calculate the volume of HCl gas (in dm³) needed to react completely with 2.0 g of ethene at room temperature and pressure (assume ideal gas behaviour, molar volume = 24 dm³/mol).

Answer: Moles of ethene = 2.0 g / 28 g/mol = 0.0714 mol; Since 1 mol of ethene reacts with 1 mol of HCl, HCl needed = 0.0714 mol; Volume = 0.0714 mol × 24 dm³/mol = 1.72 dm³.

Question 2: Explain how the reactions of alkenes are important in the production of plastics and other polymer materials.

Answer: Alkenes such as ethene and propene undergo polymerisation reactions, where monomers link to form long-chain polymers used in plastics, packaging, and textiles. These reactions are significant in industry because they allow mass production of versatile materials with useful properties.