4 (obtaining and using metals) - exam qs

• What is the reaction of the extraction of aluminium from its ore?

  Reduction
• What is an alloy?

  A mixture of one or more metals
• Explain, in terms of their structures, why magnalium is stronger than pure aluminium

  In pure aluminium, the atoms are all the same size and the layers slip over one another easily. The magnesium atoms in magnalium are bigger than the aluminium atoms and disrupts the regular arrangement preventing the layers from sliding over one another. This makes it stronger.
• What is reduction?

  Loss of oxygen or gain of electrons
• Explain why electrolysis is used to extract aluminium but is not used to extract iron:

  Iron is below carbon in the reactivity series meaning it only needs to be heated with carbon to extract it from its core. It is a waste of money to use electrolysis on iron.
• What is the formula of zinc chloride?

  ZnCl2
• Explain why aluminium is extracted by a different method rather than heating the ore with carbon.

  Aluminium is too stable so carbon is not strong enough of a reducing agent to produce aluminium from its ore
• Pure metal can be converted into alloys. In many cases alloys are more useful than pure metals, for example they are stronger. Gold alloys, stainless steel and nitinol are examples of useful alloys. Describe how alloying improves the usefulness of metals.


  Making a pure metal an alloy increases hardness, decreases malleability and increases corrosion resistance. Gold alloys are used for jewellery, stainless steel is used for cutlery, steel is used for construction and nitinol is used for spectacle frames.
• When tin oxide reacts with carbon to form products, is tin oxide or carbon reduced or oxidised?

  Tin oxide is reduced
• Explain how the method used to obtain gold is related to its position in the reactivity series and to the cost of the extraction process:

  Gold is at the bottom of the reactivity series and is found as an uncombined metal so the cost of recovery is low
• Explain how the method used to obtain iron is related to its position in the reactivity series and to the cost of the extraction process:

  Iron is in the middle of the reactivity series and is found combined with other elements. Electrolysis can be used but it is not needed as it can and is extracted by heating with carbon.
• Explain how the method used to obtain aluminium is related to its position in the reactivity series and to the cost of the extraction process:

  Aluminium is near the top of the reactivity series and is found combined with other elements. It is extracted by electrolysis as it is very difficult to reduce and the use of electricity makes this method expensive.