2024

• Alkanes and alkenes are hydrocarbons
• hydrocarbon D-

  Molecules made up of carbon and hydrogen atoms only
• general formula for alkanes is $C_nH_{2n+2}$


  E.g what is formula for an alkane with 10 carbon atoms=$C_{10}H_{22}$
• Explain how crude oil is separated into fractions

  -Crude oil is heated

  -so some of the hydrocarbons vaporise

  -The column has a temp gradient.

  -And the fractions condense at their boiling points
• Describe the test for alkenes

  test-add bromine water

  result-bromine water changes from orange to colourless
• What type of substance is poly(propene)

  Polymer
• catalyst D-

  A substance that increases the rate of reaction and is not used up during the reaction.
• What are catalysts in biological systems called

  Enzymes
• Describe how crude oil was formed

  Plankton died and were buried in mud &were compressed over a million years.
• How can sulfur dioxide be produced by transport?

  Some fuels contain sulfur which reacts with oxygen to produce sulfur dioxide
• 2 problems caused by sulfur dioxide as an atmospheric pollutant

  -acid rain

  -repiratory problems(in humans)
• Describe how carbon monoxide can be produced by transport

  -Fuels are burnt in limited oxygen
• why did red colour not move

  Red colour is insoluable in the solvent so doesnt move
• Why were they on 3 colours visible on the chromatogram

  -The other colour may be white

  -2 of the other colour may be insoluble
• use a different solvent

  to show there are 4 colours in the printer or whatever ink
• if forward reaction releases 198kJ/mol of energy the reverse reaction will

  <198kJ/mol
• If increased concentration of oxygen

  Equilibrium shifts to the right
• If pressure decreased

  Equilibrium shifts to the left
• The temperature is increased

  Equilibrium shifts to the left
• What effect does a catalyst have on the position of the equilibrium

  effect-equlibirum doesnt chnage

  reason-increases the rate of the forward reaction & inverse reaction equally.
• One con of using distillation to produce potable water

  large amount of energy is required
• Describe one other method to produce potable water from seawater

  Reverse osmosis using membranes
• Give 2 methods that can be used to extract copper from these leachate solutions

  -displacement using scrap iron

  -electrolysis
• Describe how the metal compounds are obtained from the plants

  plants are harvested & burned to produce ash that contains metal compounds
• A student investigated the effect of changing the particle size of calcium carbonate on the rate of reaction with hydrochloric acid. Describe a method the student could use to produce valid results. (6 marks)A:

  • Measure the volume of hydrochloric acid using a measuring cylinder
  • Measure the mass of calcium carbonate using a balance
  • Add the hydrochloric acid to the calcium carbonate in a conical flask
  • Seal the flask with a stopper and delivery tube and start the timer
  • Record the volume of gas collected at set time intervals or time how long it takes to collect a fixed volume
  • Repeat using different particle sizes of calcium carbonate
  • Keep the mass of calcium carbonate the same each time
  • Use the same volume and concentration of hydrochloric acid
  • Keep the temperature constant
  • Repeat each experiment to ensure reliability and spot anomalies
• The student investigated the effect of increasing the temperature on the rate of a reaction.Explain the effect of increasing the temperature on the rate of a reaction.Refer to particles and collisions in your answer. (3 marks)A:

  • Increasing the temperature increases the energy of the particles
  • Particles move faster and collide more frequently
  • A greater proportion of collisions have enough energy to be successful (activation energy is reached)