chemical changes

• what is the neutral ph?

  7
• what is the most acidic ph?

  0
• what is the most alkali ph?

  14
• what are 2 ways to measure ph?

  • universal indicator - a wide range indicator that changes colour depending on ph. gives an approximate ph value
  • ph probe - gives an accurate value of ph
• what is a word neutralisation reaction?

  acid + base -> salt + water
• what is a symbol neutralisation reaction?

  h+ + oh- -> h2o
• what are titrations?

  used to find the exact volume of acid needed to neutralise a quantity of alkali. the results can be used to calculate the acid or alkali concentration
• what are the 3 reactions of acids?

  • acid + metal carbonate -> salt + water + carbon dioxide
  • acid + metal oxide -> salt + water
  • acid + metal hydroxide -> salt + water
• how are soluble salts made?

  adding metals / insoluble metal compounds to acids. excess solids are filtered off and remained salt solution is crystallised
• what salt is produced if hydrochloric acid (HCl) is used?

  chloride
• what salt is produced if sulfuric acid (H2SO4) is used?

  sulfate
• what salt is produced if nitric acid (HNO3) is used?

  nitrate
• what is a strong acid?

  An acid that completely dissociates in water to produce hydrogen ions
• what are 3 examples of strong acids?

  • hydrochloric
  • sulfuric
  • nitric
• what is a weak acid?

  an acid that partially dissociates in water to produce hydrogen ions
• what are 3 examples of weak acids?

  • ethanoic
  • citric
  • carbonic
• what is ph?

  The measure of acidity or alkalinity in a solution.
• what is acid strength a measure of?

  proportion of acid molecules that ionise in water
• what is acid concentration?

  number of acid molecules in a certain volume of water
• what is the reactivity scale from highest to lowest?

  • potassium
  • sodium
  • lithium
  • calcium
  • magnesium
  • carbon
  • zinc
  • iron
  • hydrogen
  • copper
• what metals can be extracted from molten compounds using electrolysis?

  • potassium
  • sodium
  • lithium
  • calcium
  • magnesium
• what metals can be extracted from oxides by reduction using carbon?

  • zinc
  • iron
  • copper
• what is the product made from metal + oxygen?

  metal oxide
• what is the product made from metal + acid?

  salt + hydrogen
• what is the product made from metal + water?

  metal hydroxide + hydrogen
• what metals create an explosive reaction with cold, dilute acid?

  • potassium
  • sodium
  • lithium
  • calcium
• what metals create a moderate reaction with cold, dilute acid?

  • magnesium
  • zinc
  • iron
• what metal has no reaction with cold, dilute acid?

  copper
• what metals have a reaction with water?

  • potassium
  • sodium
  • lithium
  • calcium
• what metals have no reaction with water?

  • magnesium
  • zinc
  • iron
  • copper
• what is a displacement reaction?

  when a more reactive element displaces a less reactive metal from its compound
• what is oxidation?

  • gain of oxygen
  • loss of electrons
• what is reduction?

  • gain of electrons
  • loss of oxygen
• what is a redox reaction?

  where one substance in a reaction is reduced and another is oxidised
• what do ionic equations show?

  • particles that react
  • products they form
• what is an example of an ionic equation?

  magnesium + zinc chloride -> magnesium chloride + zinc
• Why can ionic compounds conduct electricity when molten or dissolved in water?

  Because ions are free to move
• What are the reactions taking place at the electrodes during electrolysis?

  Reduction at the cathode, oxidation at the anode
• Why can't solid ionic compounds conduct electricity?

  The ions are locked in place
• What happens to the forces of attraction in ionic compounds when they are melted or dissolved?

  They are broken, allowing ion movement