Paper 2

• What are the two equations for mean rate of reaction?

  Quantity of reactant used/time taken OR Quantity of product used/time taken
• What are the units of rate of reaction?

  g/s OR $cm^3$/s
• What factors affect rate of reaction?

  The concentration of reactants in solution

  The pressure of reacting gases

  The surface area of solid reactants

  The temperature

  The presence of catalysts.
• What do catalysts do?

  Increase the rate of reaction, by lowering the activation energy (they are not used up during the reaction)
• What does this sign mean? $\leftrightarrow$


  Reversible
• What is dynamic equilibrium?

  Where the forward and reverse reaction occur at equal rates
• What is the abundance of oxygen in the current atmosphere?

  21%
• What is the abundance of nitrogen in the current atmosphere?

  78%
• What is the abundance of carbon dioxide in the current atmosphere?

  0.04%
• What is the abundance of argon in the current atmosphere?

  0.9%
• Which two planets have an atmosphere that are like the atmosphere Earth was believed to have when it was young?

  Mars and Venus
• What happened on Earth that led to the atmosphere changing?

  Evolution of life (cyanobacteria, algae and later plants) that photosynthesised.
• Describe how these sedimentary rocks formed starting from carbon dioxide in the air via soluble compounds in oceans

  Co2 dissolved in oceans

  Formed soluble compounds

  Animals take in these compounds which become part of their skeletons/exoskeletons

  These fall into sediment as animal dies

  Sediment becomes sedimentary rock over millions of years
• How did oceans form?

  Water vapour released by volcanoes during volcanic activity, condensed as Earth cools
• Give two ways Co2 is removed and added to the atmosphere

  Removed:

  Dissolved in oceans

  Photosynthesis

  Added:

  Burning of fossil fuels

  Respiration
• How is sulfur dioxide formed?

  Sulfur in fuel reacts with oxygen in air
• What is the problem caused by sulfur dioxide?

  Acid rain
• How is carbon monoxide formed?

  Carbon from fuels reacts with oxygen in incomplete combustion
• How are nitrogen oxides formed?

  Nitrogen in air reacts with oxygen at high temperatures
• What is the problem caused by carbon monoxide?

  Toxic
• What is the problem caused by nitrogen oxides?

  Acid rain
• Why can methane and carbon dioxide (greenhouse gases) absorb Earth’s infra radiation but not the Suns?


  Earth’s infrared radiation has longer wavelength
• Explain why the amount of methane is increasing in the atmosphere?

  More waste in landfill

  More agriculture
• Give three potential consequences of global warming?

  Rising sea levels

  More frequent extreme weather events

  Migration of species
• Give three ways the amount of greenhouse gases released can be controlled/reduced?

  Renewable energy

  Carbon capture and storage

  Carbon taxes
• If you increase the concentration of a reactant, the equilibrium will shift in the forward reaction to make more product
• If you decrease the concentration of the reactant, the equilibrium will shift in the reverse reaction
• If you increase the temperature, the equilibrium will shift in the endothermic direction
• If you decrease the temperature, the equilibrium will shift in the exothermic direction
• If you increase the pressure, the equilibrium will shift in the direction of the fewest gas molecules
• If you decrease the pressure, the equilibrium will shift in the direction of the most gas molecules
• What is crude oil?

  The remains of an ancient biomass consisting mainly of plankton that was buried in mud
• Alkanes are saturated hydrocarbons, meaning they contain only single bonds between carbon atoms
• Alkenes are unsaturated hydrocarbon, meaning they contain double bonds between carbon atoms
• The general formula for alkanes is CnH2n+2
• What are the first four alkanes?

  Methane

  Ethane

  Propane

  Butane
• How can hydrocarbons in crude oil be separated into fractions?

  Fractional distillation
• The fractions produced in fractional distillation can be processed to produce fuels and feedstock for the petrochemical industry.
• How does fractional distillation work

  • Crude oil is heated to vaporise (the hydrocarbons)
  • There is a temperature gradient in the (fractionating) column
  • (so) the gases condense at different levels
  • (because of their) different boiling points
• What is the equation for complete combustion?

  fuel + oxygen ----> carbon dioxide + water