paper 2 questions

• The student investigated the effect of changing the fuel on the mass of fuel needed to heat the water.

  The student used an identical spirit burner filled with pentanol, another liquid fuel.

  Give two variables that the student should keep the same in this investigation.

  • distance from beaker to {flame/wick/burner} (1)

  • size of wick (1)

  • volume of water (1)

  • temperature increase of water (1)

  • {size/shape/type} of beaker (1)
• Suggest two improvements that the student could make to their apparatus so that more of the heat energy is transferred to the water. - spirit burner

  • move beaker closer to spirit burner (1)

  • use a metal {calorimeter/beaker} instead of glass (1)

  • use (draft) shields (1)

  • place a lid on the beaker (1)

  • insulate the (sides of the) beaker (1)
• Acid rain is caused by some pollutant gases present in the atmosphere.

  Explain how impurities in fossil fuels can result in acid rain.

  • sulfur/ S (is present as an impurity) (1)

  • (when fuel burns) {impurity/sulfur} is

  {burned/ combusted/ oxidised/ reacts with

  oxygen} (1)

  • sulfur dioxide/ SO2 (formed) (1)

  • sulfur dioxide dissolves in {rain/ water/

  clouds} (1)

  • sulfuric acid is formed (1)
• Explain one precaution that should be taken when preparing the sample of chlorine gas.

  • • use a fume cupboard (1)
  • • because (chlorine/it) is a toxic gas (1)
  • ventilated room
  • allow poisonous
  • OR
  • • wear gloves/ goggles/ safety glasses (1)
  • • because the concentrated hydrochloric acid is
  • corrosive (1)
  • allow acids ‘burns’ skin/ eyes
  • OR
  • • do not dispose of any reactants / products down
  • the drain (1)
  • • because {potassium manganate/ chlorine /it}
  • is hazardous to the environment (1)
• State the purpose of the delivery tube. - chlorine

  so {gas / chlorine} moves (from flask) to gas jar
• Suggest why damp blue litmus is placed at the top of the gas jar.- chlorine

  • chlorine will turn the damp litmus paper (red

  then) white / bleached (1)

  • so that you can see when the jar is full (1)
• Describe how the fermentation of glucose is carried out FERMENTATION

  • dissolve glucose in water to form a solution

  • place glucose solution in a suitable flask

  • add yeast to glucose solution

  • place fermentation mixture in warm room

  • fit air lock or equivalent in neck of flask

  • reaction stops when bubbles stop

  • filter out yeast
• how the dilute solution of ethanol produced can then be processed to form a concentrated solution of ethanol.

  CONCENTRATION

  • fractional distillation

  • place the dilute ethanol in round bottom flask

  • and a thermometer on top of the of fractionating column

  • add condenser to top of fractionating column

  • run water into bottom of condenser

  • heat round bottom flask

  • to above boiling point of ethanol

  • collect concentrated ethanol from end of condenser
• A solution of a chloride salt is acidified with dilute nitric acid.

  Silver nitrate solution is added to the mixture.

  Describe what is seen when the silver nitrate solution is added.

  white precipitate
• is lead chloride insoluble in water?

  yes, lead chloride is insoluble in water