Alkenes Quiz
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5 questions, one answer each
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1. What is the general formula for alkenes?
- A. CnH2n+2
- B. CnH2n
- C. CnH2n+1OH
- D. CnH2n+1COOH
2. How are alkenes typically manufactured industrially?
- A. By fractional distillation of crude oil directly
- B. By cracking larger alkane molecules at high temperature with a catalyst
- C. By reacting alkanes with chlorine under UV light
- D. By fermenting glucose with yeast
3. What happens when aqueous bromine is shaken with an alkene?
- A. It turns blue
- B. It stays orange/brown, showing no reaction
- C. It is decolourised, showing the presence of a C=C double bond
- D. It forms a white precipitate
4. Which catalyst is used when steam adds to ethene to make ethanol?
- A. Nickel catalyst
- B. Acid catalyst
- C. Iron catalyst
- D. Vanadium(V) oxide catalyst
5. A student has two unlabelled hydrocarbon samples, X and Y, both liquid at room temperature. When shaken with aqueous bromine, sample X decolourises it while sample Y does not. Using this evidence, explain what can be concluded about each sample and describe an addition reaction sample X could undergo.
- A. X is saturated and Y is unsaturated; X could react with chlorine under UV light
- B. X is an alkene (unsaturated, contains a C=C bond) and Y is an alkane (saturated); X could undergo an addition reaction with hydrogen using a nickel catalyst to form an alkane
- C. X and Y are both alkanes; X simply contains more carbon atoms than Y
- D. X is a carboxylic acid; the colour change is due to acid-base reaction with bromine