Chem paper 2 2022 errors

• Results obtained that are similar on different days in the same conditions by the same student are repeatable
• SHOW WORKINGS
• Formation of oxides of nitrogen in car engines


  1. Nitrogen and oxygen react

  2. At higher temperatures
• As molecular size increases


  Viscosity increases
• Carbon dioxide decreased in early atmosphere
• Carbon dioxide was dissolved in oceans, NOT because of photosynthesis
• Deposits of natural gas formations

  1. Plankton died

  2. Covered by sediment

  3. Subjected to high temperatures and pressure (over millions of years)
• In graphs, higher concentration means there is a steeper initial curve but the same start point and same plateau
• nitrogen is from the air/ atmosphere
• hydrogen is a natural gas
• coal is formed when plants die and are covered by mud and then compressed over time
• 100% atom economy as there is one product
• higher temperature means higher rate as there are more frequent collisions and more particles have activation energy
• higher pressure means higher rate as there are more frequent collisions
• catalyst increases rate as it lowers activation energy
• cold temperature means that equilibrium will shift to favour the exothermic reaction
• hotter temperatures means that equilibrium will shift to favour the endothermic direction
• higher pressure shifts equilibrium to the side with fewer molecules
• catalysts have no effect on the position of equilibrium
• higher temperature = higher energy = higher costs
• higher pressure = higher energy = higher costs
• higher pressure = stronger reaction vessels = higher costs
• catalyst = lower energy costs
• temperature is a compromise between rate and position of equilibrium
• temperature is a compromise between rate and cost
• pressure is a compromise between yield, rate and cost
• read questions
• test tube is heated until mass didn’t change so that the reaction is complete
• energy = new mass / old mass x old energy
• crude oil is heated to vaporise the hydrocarbons
• detergents and solvents are produced from feedstock
• oxygen = half the moles (in balancing equations) as it is diatomic
• sulfur dioxide causes:

  1. acid rain
  2. respiratory problems

  as it is toxic
• poly(butene) insulation must be removed from copper before recycling or:

  1. copper produced would be impure, a mixture or could be contaminated
  2. insulation would burn/ melt during recycling
• scrap copper -> new copper water piper:

  1. (wire heated until) copper melts
  2. recast/ reform copper (into pipes)
• recycling scrap copper is more sustainable as it:

  1. uses less energy
  2. conserves copper ores (finite resource)
  3. (produces) less waste
• halide ions: precipitated when mixed with silver nitrate and nitric acid
• chloride ions: white precipitate
• bromide ions: cream precipitate
• iodine ions: yellow precipitate