2021

• How does increasing the temperature affect the rate of reaction

  The rate increases because particles have more energy, so more frequent collisions.
• Crude oil is formed by the decomposition of

  plankton/ancient biomass
• 3 carbon atoms

  propane
• Test for alkenes

  test-bromine water

  result-turn from orange to colourless in the presence of an alkene.
• How copper sulfate can be used as a test for the presence of water

  Add water to anhydrous copper sulfate. Colour changes from white to blue.
• Pure substance meaning

  A single element or compound
• Explain how distillation is used to obtain potable water from salty water

  -Heat salty water

  -so water evaporates (as water vapour)

  -cool the water vapour

  -which condenses to form potable water
• Obtaining potable water from salty water is more expensive than obtaining potable water from groundwater.why???

  -Distillation requires energy to boil salty water but groundwater only needs filtering and sterilising.
• phytoming

  is uses to extract copper from low-grade ores
• phtomining process

  1-plants absorb metal compounds

  2- plants are harvested

  3 -plants are burned

  4-copper compounds from ash are dissolved in acid

  5-solution of copper compounds is electrolysed
• Give 2 con of phytomining compared with traditional mining methods

  -cost

  -pytomining is slower to produce copper

  -large area of land required
• Describe how nitrogen dioxide is produced in the engine of a car that burns fossil fuels

  At high -temperature (in the engine).Nitrogen reacts with oxygen to produce nitrogen dioxide.
• finite resource meaning-

  A source which will eventually run out
• $CO_2$ test 


  use limewater which doesnt turn milky/cloudy
• Explain how a catalyst increases the rate of reaction

  provides an alternative pathway which lowers the activation energy.
• How does a catalyst affect the equilibrium position

  equilibrium position stay the same .increases the rate of forward and reverse reactions by the same amount.
• increase pressure

  yield increases
• increase temp

  yield decreases.Because the system shifts in an endothermic direction.
• Q: Give the independent variable and one control variable in this investigation. (2 marks)A:

  • Independent variable: Concentration of hydrochloric acid
  • Control variable: Temperature of hydrochloric acid (or) Volume of hydrochloric acid (choose one — either is correct)
• Q: Compare the structure and properties of methane and hexane. (6 marks)A:

  • Methane has 1 carbon atom bonded to 4 hydrogen atoms
  • It is a small molecule with weaker intermolecular forces
  • Therefore, it has a lower melting point (-183 °C) and boiling point (-162 °C)
  • Methane is a gas at room temperature
  • Hexane has 6 carbon atoms bonded in a chain with 14 hydrogen atoms
  • It is a larger molecule with stronger intermolecular forces
  • This gives hexane a higher melting point (-95 °C) and boiling point (69 °C)
  • Hexane is a liquid at room temperature
• suggest one reason why the trend can't be used to accurately predict the future world production of copper

  -more use of recycling

  -copper is finite so may run out
• Q: Explain why carbon dioxide emissions during use and operation are not the total carbon footprint for a car.Refer to the stages of the life cycle assessment of a car in your answer. (3 marks)A:

  • Carbon dioxide is also emitted during the extraction of raw materials
  • It is released during the manufacturing process
  • CO₂ is also produced during the disposal or recycling at the end of the car’s useful life