Chapter 5 Practice Paper: Organic Chemistry — question paper

Section A: Multiple-choice questions[10 marks]

Choose the one correct answer for each question.

1. 1

   Crude oil is best described as

   1. Aa compound of carbon only
   2. Ba mixture of hydrocarbons
   3. Ca solution of salts in water
   4. Da pure liquid with one boiling point
   ( )
2. 2

   The fraction collected nearest the top of a fractionating column has

   1. Athe smallest molecules and the lowest boiling range
   2. Bthe largest molecules and the highest boiling range
   3. Cthe blackest colour and thickest texture
   4. Dno useful purpose
   ( )
3. 3

   Which equation is balanced for the complete combustion of ethane?

   1. AC₂H₆ + O₂ → 2CO₂ + 3H₂O
   2. B2C₂H₆ + 5O₂ → 4CO₂ + 6H₂O
   3. C2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
   4. DC₂H₆ + 3O₂ → 2CO₂ + 2H₂O
   ( )
4. 4

   Aqueous bromine is shaken with hexane (an alkane). The colour of the mixture

   1. Achanges from colourless to orange
   2. Bimmediately turns colourless
   3. Cturns blue-black
   4. Dstays orange
   ( )
5. 5

   Liquid vegetable oil is hardened into margarine by adding hydrogen

   1. Aacross some C=C bonds over a nickel catalyst
   2. Bin ultraviolet light
   3. Ctogether with chlorine
   4. Dduring fermentation by yeast
   ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided. Show all necessary working. Give numerical answers to 3 significant figures where appropriate, with units.

1. 1

   Crude oil is separated into useful fractions in a fractionating tower.

   1. (a)

      State why the crude oil is heated strongly before it enters the tower.

      [1]
   2. (b)

      Fraction P boils at about 40 °C and fraction Q at about 300 °C. State which leaves the tower higher up, and explain your choice.

      [2]
   3. (c)

      Describe and explain the trend in viscosity and colour of the fractions from the top to the bottom of the tower.

      [2]
   4. (d)

      Name the fraction valued as a feedstock for making plastics.

      [1]
2. 2

   Ethene, C₂H₄, and propene, C₃H₆, are the two smallest alkenes.

   1. (a)

      State the homologous series to which propene belongs, its general formula, and the feature of its structure that makes it unsaturated.

      [2]
   2. (b)

      Write the equation for ethene reacting with hydrogen, and state the condition used.

      [2]
   3. (c)

      Describe what is observed when aqueous bromine is shaken with ethene, write the equation for the reaction, and name the reaction type.

      [3]
3. 3

   A brewery ferments sugar solution to make ethanol for blending into fuel, and a small sample of the ethanol is later oxidised in the laboratory.

   1. (a)

      Write the balanced equation for the fermentation of glucose, C₆H₁₂O₆.

      equation =[2]
   2. (b)

      State two conditions for a good yield in step (a) and give one reason for each.

      [2]
   3. (c)

      Name the type of reaction that converts ethanol to ethanoic acid, give one reagent/condition for it, and write the equation using [O].

      [3]