Chemistry Paper

Chemistry Answers

  3) The color of solution will turn from Blue to Colorless.
      The color of solid will turn to a Pink-Brown coating

  4) AL-Electrolysed
      Zn-Thermal Reduction
      Cu-Thermal Reduction or found as an element

  5) Fe(s) + H2SO4(aq) --- FeSO4(aq) + H2(g)
      OBSERVATIONS:
      Solution changes from colorless to green
      Fe shrinks as it reacts with an acid

  6) i) X>Z>W>Y
      ii) Z

  7) i)K>Mg>Zn>Fe>Cu
  ii) Between Fe and Cu
  iii) Because Cu can not displace H while Fe can
  iv) Galvenizing means coating a substance with thin layer of Zn. It is done to
  prevent rust

  8) a) i) Thermite Process
      ii) Displacement rxn means a more reactive metal is used to displace a less reactive metal from its compound
      b) Oxidized: Al                       Reduced: Fe2O3

  9) i) Heametite
      ii) Silica (sand)
      iii) Pic Iron

  10) Ca>Mg>Zn>Cu

  b) Reaction: Ca + H2O
  Observations: Bubbles of H2 gas
  Milky solution

  11) a) i) Heametite       ii) Limestone
  b) CO
  Equation: Fe2O3 + 3Co----2Fe + 3CO2
  c) CaCO3 ------- CaO + CO2 (Thermal Decomposition)
  The CaO is used to make slag

  12) Al. Because as soon as Al is exposed to air, a small layer of Aluminium Oxide is formed. The layer stops it from reacting from any other thing and at first the reaction is slow.
  13) i) No Change
      ii) Blue solution turns green and there will be a red-brown coating
  14) Al2O and Fe
  15) a) Fe, b) K, c) Zn, d) Fe,Zn, e)Cu
  16) a) i) Heametite-Fe2O3
  ii) Limestone-CaCO3
  b) Gas:CO
  Equation: 1) C + O2 ------- CO2
  2) Co2 + c ------- 2CO

  17) b) Costly to maintain temperature, High melting Point and Expensive
        c) Al+3 + 3e- --------- Al
        d) At high temperature C will be reacting with O2. Carbon blocks will become thinner.     C + O2 --------- CO2
        e) Use: Used for overhead electrical cables
          Property: Good...