chemical changes

• define ores


  metal rich compounds
• name of positive electrode


  anode
• name of negative electrode


  cathode
• what are water's ions?

  hydrogen (H+)

  hydroxide (OH-)
• what type of ion will be attracted to cathode?

  positive
• what type of ion will be attracted to anode?

  negative
• if a halide is present at the anode, does OH- get discharged?

  no, if halide is present it is always discharged
• which gets discharged at cathode?

  if metal is more reactive than hydrogen, hydrogen gets discharged
• making salts steps


  add dilute acid to beaker

  add metal oxide until in excess

  wait for effervescence to stop

  filter

  heat

  wait to evaporate
• define activation energy

  minimum amount of energy reactant particles need in order to collide w/ each other and react
• what does the ph scale measure?


  how acidic or alkaline a substance is
• what is considered acidic on the ph scale?


  1-6
• what is considered neutral on the ph scale?


  7
• what is considered alkaline on the ph scale?


  8-14
• how can you measure ph?


  universal indicator (red -> blue/purple)

  ph meter (more accurate, removes human error)
• what is an acid?


  any substance that forms an aqueous solution with a ph less than 7 - release H+ ions
• what is an alkali?


  a base that dissolves in water to form a solution with a ph more than 7 - release OH- ions in water
• what are bases?


  any substance with a pH less than 7
• what do strong acids do in aq solutions?


  ionise completely and release H+ ions (protons)

  e.g:

  HCl -> H^+ + Cl- (hydrochloric acid)

  HNO3 -> H^+ + NO3- (nitric acid)
• what do weak acids do in aq solutions?


  partially ionise

  small portion dissociate to release OH-

  ionisation is reversible

  (ethanoic, carbonic, citric)
• what is ph?


  measure of H+ ions in a solution

  higher H+ = lower ph

  7 -> 6 (on ph scale) -> 10 x H+
• neutralisation reactions in metals


  metal oxide + acid -> salt + water

  metal hydroxide + acid -> salt + water

  metal carbonate + acid -> salt + water + carbon dioxide

  soluble salt = acid + insoluble base
• making salts practical steps


  1. heat acid until warm then add solute, stirring constantly until it stops disappearing
  2. filter mixture to remove excess base, transfer solution to evaporation basin
  3. evaporating water from solution using a bunsen burner until crystals appear
  4. remove evaporating basin from heat and allow filtrate to dry and crystalise
• what is the reactivity series?

  potassium

  sodium

  lithium

  calcium

  magnesium

  carbon

  zinc

  hydrogen

  copper
• what is the mnemonic for the reactivity series?


  King Sam Loves Catching Mice, Cats Zoom Happily Chasing
• what is oxidation in the context of extracting metals?


  gaining oxidation
• what is reduction in the context of extracting metals?


  losing oxygen
• most metals from metal oxides except unreactive metals that are found as pure metals
• what must you do to get pure metals from ores?

  reduce metal oxides

  for metals less reactive than carbon

  • metal oxide + carbon -> pure metal + carbon dioxide
• what is the acronym for redox reaction?


  Oxidation -> loss of e-

  Is

  Loss

  Reduction -> gain of e-

  Is

  Gain
• redox reactions

  
• what is electrolysis?


  splitting with electricity?
• in what substances does electrolysis work 


  metals

  aq

  molten
• equipment needed for electrolysis?


  beaker containing electrolyte

  electrodes (copper or carbon)

  negative - cathode

  positive - anode

  wire joining electrodes + power supply
• what is an electrolyte?


  liquid w ionic compound in which ions are free to move and conduct electricity
• electrolysis practical

  A)