Reactivity series

• Reaction of metals with cold water

  *more reactive metals reacts violently with cold water

  metal+water->metal hydroxide + hydrogen
• The order of reactivity of metals can be determined by the reactions of metals with:

  1. cold water
  2. steam
  3. dilute hydrochloric acid
• Metal + steam -> metal oxide + hydrogen

  
• Potassium reacts very violently wth cold water to form potassium hydroxide

  2K(s)+2H2O(l)->2KOH(aq)+H2(g)
• sodium reacts violently with cold water to form sodium hydroxide and hydrogen gas

  2Na(s)+2H2O(l)->2NaOH(aq)+H2(g)
• calcium reacts with cold water readily to form calcium hydroxide and hydrogen gas

  Ca(s)+2H2O(l)->Ca(OH)2(aq)+H2(g)
• magnesium reacts very slowly with cold water to form magnesium hydroxide and hydrogen gas

  Mg(s)+2H2O (l)->Mg(OH)2 (s)+H2(g)
• Potassium, sodium, calcium react explosively in steam
• Hot magnesium reacts violently with steam to form magnesium oxide (white solid) and hydrogen gas. A bright white glow is produced (magnesium)
• Hot zinc reacts readily with steam to produce zinc oxide and hydrogen gas. Zinc oxide is yellow when hot and white when cold
• red-hot iron reacts slowly with steam to form iron oxide. the iron must be constantly heated for the reaction to progress
• lead, copper, silver does not react with steam
• zinc, iron, lead, copper and silver does not react with cold water
• metals above hydrogen in the reactivity series react with hydrochloric acid to produce hydrogen gas
• metal chloride and hydrogen formed when metal react with dilute hydrochloric acid
• effervescence observed and metal dissolves when metal react with dilute hydrochloric acid
• Metal oxide react with carbon to form metal and carbon dioxide
• only the metal oxides below carbon can be reduced by carbon
• the lower the metal is in the reactivity series from carbon, the more readily the reduction of the metal oxide will occur
• metal oxide and hydrogen react to form metal and steam
• a more reactive metal can displace a less reactive metal from its salt solution
• copper metal is pink when freshly formed before turning red-brown subsequently
• In a metal displacement reaction, the more reactive metal is oxidises and less reactive metal is reduced
• a more reactive metal has a greater tendency to form positive ions compared to a less reactive metal
• a more reactive metal can reduce the oxide of a less reactive metal
• the more reactive the metal, the more thermally stable the metal carbonate and hence the more difficult it is to decompose the carbonate by heat
• the thermal stability of metal carbonates can be tested by heating the carbonate in a dry test tube
• potassium carbonate and sodium carbonate are unaffected by heat
• calcium, magnesium,zinc,iron(II),Lead(II),Copper(II) carbonate decomposes into metal oxide and carbon dioxide on heating
• silver carbonate decompose into silver and carbon dioxide. the silver oxide produced is thermally unstable and will further decompose to form silver
• the reactivity series can be used to predict the

  1. behaviour of a metal from its position in the reactivity series
  2. the position of an unfamiliar metal in the reactivity series from a given set of experimental results
• very unreactive metals occur freely in nature as uncombined metals
• most metals exist in the form of ores
• potassium, sodium, calcium and magnesium are extracted by electrolysis
• zinc, iron,lead copper silver are extracted by reduction with carbon
• rusting or the corrosion of iron is the slow oxidation of iron to form hydrated iron (III) oxide rust
• the presence of both oxygen (in air) and water are necessary for rusting to occur
• metals cleaned with sandpaper to remove any oxides present
• presence of sodium chloride and acidic substances speed up the rusting rate
• rusting can be prevented by barrier methods or sacrifical protection