Question 1: Define an alkene and describe its general structural formula.

Answer: An alkene is a hydrocarbon with at least one carbon-carbon double bond, with the general formula CnH2n.

Question 2: Explain the mechanism of electrophilic addition in alkene reactions.

Answer: Electrophilic addition involves the attack of the electron-rich double bond by an electrophile, forming a carbocation intermediate, followed by nucleophilic attack to form the product.

Question 3: Name two common reactions of alkenes.

Answer: Hydration (adding water) and halogenation (adding halogens).

Question 1: Calculate the number of hydrogen atoms in the molecular formula of butene (C4H8).

Answer: 8 hydrogens

Question 2: If 50 grams of ethene (C2H4) reacts completely with bromine (Br2), how many moles of bromine are used? (Atomic masses: C=12, H=1, Br=80)

Answer: 0.625 moles of bromine

Question 1: Describe a safe method to test whether an unknown hydrocarbon is an alkene.

Answer: Add bromine water to the sample; if it decolorizes from orange to colorless, the hydrocarbon is an alkene.

Question 2: List two safety precautions to take when working with reactions involving alkenes and halogens.

Answer: Work in a well-ventilated area or fume hood; wear safety goggles and gloves.

Question 1: A student reacts ethene with water in the presence of a catalyst and observes the formation of ethanol. Explain the chemical process involved.

Answer: The process is hydration of ethene, where a water molecule adds across the double bond in the presence of a catalyst to produce ethanol.

Question 1: Describe how alkenes are used in the manufacturing of plastics.

Answer: Alkenes like ethene are polymerized to produce plastics such as polyethylene, which is used in packaging, containers, and insulation.

Question 2: Explain why alkenes are considered important in the chemical industry.

Answer: Alkenes are versatile starting materials for synthesizing a wide range of chemicals, including plastics, solvents, and pharmaceuticals. Their ability to undergo addition reactions makes them crucial in manufacturing processes and in developing new materials and technologies.