AQA Chemistry Past Paper - Notes

Question 1

Describe how to produce crystals of soluble salt from an insoluble solid and a dilute acid

aqueous + solid –> aqueous

Answer 1

(1) Mix
(2) Add the solid in excess, so you know you have used up all the acid / aqueous reactant
(3) Filter out the excess solid using a filter paper and funnel
(4) Heat solution in an evaporating basin to crystallisation point and leave to crystallise
(5) Pat dry with filter paper credit

Question 2

Compare Transition Metals to Alkali Metals

Answer 2

• All group 1 metals form ions with a +1 charge but the transition metals can form ions with variable charges
  
  • E.g. Iron can form Fe(II) or Fe(III)
• Transition metals are much harder, stronger and denser than the group 1 metals, which are very soft and light
• Transition have much higher melting points
• Transition metals are much less reactive than the group 1 metals
  
  • Transition metals react very slowly or do not react with water, oxygen and halogens whereas the alkali metals do.
  • A group 1 metal will tarnish in the presence of oxygen as a metal oxide is formed.
  • Iron on the other hand can take several weeks to react with oxygen to form iron oxide (rust) and requires the presence of water.
• Transition metals can be used as catalysts
• Transition metals form coloured compounds