metal extraction and reactivity

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Metal extraction and chemical reactivity

  • Metals have similar physical properties
  • Sodium: soft; reacts violently with air and water
  • Iron: reacts with air and water but slowly; forms rust
  • Gold: unreactive
  • Sodium> iron> gold (> = more reactive)

  1. Metal reactions

  1. With acid
  • Metal + HCl(dilute) – H2 + metal chloride
  • An order of reactivity, giving the most reactive metal first is called the reactivity series.
  • With air/ oxygen
  • Metal + O2 – metal oxide

  1. With water / steam
  • (More reactive) metal + cold water – metal hydroxide + H2
  • (Less reactive) metal + steam – metal oxide + H2
  • Iron + copper: used in everyday objects
  • Mg: construction
  • Na and K: coolants for nuclear reactors

  1. Using the reactivity series

  1. Competition reactions in the solid state
  • A More reactive metal has more tendency to form a metal ion by losing electrons than a less reactive metal.
  • More reactive metal + less reactive metal’s oxide – more reactive metal’s oxide + less reactive metal – exothermic and redox reaction
  • Fe2O3 + 2Al –Al2O + 2Fe

 Thermit reaction

Used to weld damaged railway lines; incendiary bombs

  1. Competition reactions in aqueous solutions
  • In displacement reaction, a more reactive metal will displace a less reactive metal from a solution of its salt.

  1. Identifying metal ions
  • When an alkali dissolves in water, it produces hydroxide ions.
  • Most metal hydroxides are insoluble..
  • If hydroxide ions from a solution of an alkali are added to a solution of an metal salt, an insoluble often colored metal hydroxide is precipitated from solution.
  • In some cases the precipitate dissolves in excess hydroxide, owing to the amphoteric nature of the metal hydroxide.
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  1. Amphoteric hydroxides
  • The hydroxides of metals are basic and they react with acids to form salts.
  • Some hydroxides react with strong bases such as sodium hydroxide to form soluble salts. Hydroxides of this type are said to be amphoteric.
  • Also the oxides of such metals are amphoteric as they react with both acids and alkalis.

  1. Discovery of metals
  • An ore is a naturally occurring mineral from which metal can be extracted.
  • Metals which are highly reactive are difficult to isolate.

  1. Extraction of metals from their ores.
  • Ores are: carbonates, ...

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