Chapter 14 Practice Paper: Crude oil, fuels and cracking — question paper

Section A: Multiple-choice questions[10 marks]

Choose one answer for each question. Each question is worth 1 mark.

1. 1

   Hydrocarbons are compounds of which two elements?

   1. Acarbon and hydrogen
   2. Bcarbon and oxygen
   3. Chydrogen and oxygen
   4. Dhydrogen and nitrogen
   ( )
2. 2

   The first fractions to condense near the top of a fractionating column have

   1. Athe highest boiling points
   2. Bthe lowest boiling points
   3. Cthe longest chains
   4. Dthe greatest viscosity
   ( )
3. 3

   Which formula belongs to an alkane?

   1. AC₂H₄
   2. BC₂H₂
   3. CC₃H₆
   4. DC₃H₈
   ( )
4. 4

   The products of complete combustion of methane in air are

   1. Acarbon and water
   2. Bcarbon monoxide and hydrogen
   3. Ccarbon dioxide and water
   4. Dcarbon dioxide and hydrogen
   ( )
5. 5

   As hydrocarbon chain length increases, viscosity

   1. Adecreases
   2. Bincreases
   3. Cstays constant
   4. Dbecomes zero
   ( )
6. 6

   Cracking always produces

   1. Aonly alkanes
   2. Bonly alkenes
   3. Cpolymers
   4. Dan alkane and an alkene
   ( )
7. 7

   C₈H₁₈ is

   1. Aan alkane, since 2 × 8 + 2 = 18
   2. Ban alkene
   3. Cnot a hydrocarbon
   4. Dan alcohol
   ( )
8. 8

   A student shakes a hydrocarbon with orange bromine water and it goes colourless. The hydrocarbon is

   1. Aan alkane
   2. Ba complete combustion product
   3. Can alkene
   4. Ddistilled water
   ( )
9. 9

   Refineries crack long-chain fractions mainly because

   1. Ashort-chain fractions are in higher demand than the distillation supplies
   2. Blong chains sell for more money
   3. Ccracking cleans sulfur from the oil
   4. Dcracked products are radioactive
   ( )
10. 10

    A faulty boiler with a limited air supply may produce, alongside normal products,

    1. Aonly extra CO₂
    2. Bcarbon monoxide and soot
    3. Chydrogen gas
    4. Dextra steam
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

1. 11

   Crude oil is separated in a fractionating column.

   1. (a)

      Explain how the oil is prepared and introduced so separation can happen.

      [2]
   2. (b)

      State where the longest-chain fractions condense.

      [1]
   3. (c)

      Name two fractions and give one use for each.

      [2]
2. 12

   This question is about burning propane, C₃H₈, in camping stoves.

   1. (a)

      Propane burns completely in a gas stove. Write a balanced equation for the reaction.

      [3]
   2. (b)

      The stove is used in a poorly ventilated tent. Name the two extra products that may form and explain why one of them is dangerous.

      [3]
   3. (c)

      Explain how the appearance of the flame tells the user whether combustion is complete.

      [3]
3. 13

   This question is about cracking hexane, C₆H₁₄.

   1. (a)

      State the conditions needed for cracking.

      [2]
   2. (b)

      When hexane is cracked, ethene forms together with a second product. Deduce its formula and name it.

      [2]
   3. (c)

      Explain why oil companies invest billions in cracking units.

      [2]