03 Metals

• Calcium reacts with cold water to form calcium hydroxide and produces hydrogen gas slowly.
• Magnesium burns with steam and produces magnesium oxide and hydrogen gas.
• Zinc reacts with steam fairly fast and produces zinc oxide and hydrogen gas.
• Iron has a reversible reaction with steam, producing iron (II) oxide and hydrogen gas.
• Potassium reacts with cold water, burns with a lilac flame and moves on the water surface to melt into a silvery ball, producing potassium hydroxide and hydrogen gas.
• Sodium reacts with cold water, burns with a golden yellow flame and moves on the water surface to melt into a silvery ball, producing sodium hydroxide and hydrogen gas.
• Aluminium does not react with steam as there is an aluminium oxide layer covering it.
• Potassium reacts with oxygen on gentle heating. It burns with a lilac flame and produces a white powder, which is potassium oxide.
• Sodium reacts with oxygen on gentle heating. It burns with a golden yellow flame and produces a white powder, which is sodium oxide.
• Calcium reacts with oxygen on strong heating. It burns with a brick red flame and produces a white powder, which is calcium oxide.
• Magnesium reacts with oxygen on strong heating. It burns with a dazzling white flame and produces a white powder, which is magnesium oxide.
• Aluminium reacts with oxygen on strong heating to produce a white powder, which is aluminium oxide.
• Zinc reacts with oxygen on strong heating and produces zinc oxide, which is yellow when hot and white when cold.
• Iron reacts with oxygen on strong heating. It burns with yellow sparks and produces a black solid, which is a mixture of iron (II) oxide and iron (III) oxide.
• Lead reacts with oxygen on strong heating. It does not burn and produces lead (II) oxide, which is orange when hot and yellow when cold.
• Copper reacts with oxygen on very strong heating. It does not burn and its surface turns black, which is copper (II) oxide.
• Mercury reacts with oxygen on very strong heating. It does not burn and a red powder forms on the surface, which is mercury (II) oxide.
• Potassium and sodium reacts explosively with hydrochloric acid.
• Calcium, magnesium, aluminium, zinc, iron, and lead has a moderate reaction with hydrochloric acid.

  Colourless bubbles (hydrogen gas) evolve.

  The metal turns into metal chloride and dissolves.
• Factors of availablity of a metal:

  1. abundance
  2. supply and demand
  3. cost of mining the ore
  4. cost of extracting the metal from its ore
• electrochemical series:

  K, Na, Ca, Mg, Al, Zn, Fe, Pb, Cu, Hg, Ag, Au
• Oxygen and water are essential for rusting of iron.
• Presence of acids accelerate rusting as they promote the dissolving of iron.
• Presence of electrolytes accelerate rusting as they increases the conductivity of the solution.
• Heat accelerates rusting as increase in temperate increases the rate of reaction.
• Rusting is faster if it is connected to a metal less reactive than iron. The less reactive metal receives electrons from iron and thus speed up the transfer of electrons.
• Presence of impurities, pointed or deformed regions in iron accelerate rusting.
• Rust indicator contains potassium hexacyanoferrate (III), phenolphthalein, and sodium chloride.
• Iron (II) ions turn potassium hexacyanoferrate (III) from yellow to deep blue.
• Hydroxide ions turn phenolphthalein from colourless to pink.
• Sodium chloride is present in rust indicator as an electrolyte to speed up rusting.
• Sacrificial protection is when iron is connected to a more reactive metal such that the more reactive metal will give up electrons instead.
• Galvanization is a form of sacrificial protection where iron is covered with a thin layer of zinc.