This reaction is used by a jewellery workshop to recover copper from a solution containing copper sulfate. A strip of magnesium is placed in the blue soluti...
Question 1 Report
This reaction is used by a jewellery workshop to recover copper from a solution containing copper sulfate. A strip of magnesium is placed in the blue solution. Fig. 1 shows the observations after several minutes. The workshop records the mass of copper collected, rather than throwing the metal-containing waste away. Magnesium is higher than copper in the reactivity series.
(a) Name the type of reaction taking place. [1]
(b) Describe two visible changes expected in the beaker. [2]
(c) Use the reactivity series to explain why magnesium, but not gold, could remove copper from this solution. [2]
A university archive has a sample of gold leaf used to decorate an old book cover. Fig. 1 compares the arrangement of particles in gold metal with particles in diamond, a form of carbon. Gold can be hammered into thin sheets, but diamond is extremely hard. The archive conservator needs a scientific explanation for these different properties.
(a) Name the type of structure in diamond. [1]
(b) Describe the bonding between carbon atoms in diamond. [2]
(c) Explain why gold can be shaped into leaf. [2]
Answer Details
Magnesium in copper sulfate
(a) This is a displacement reaction. [1]
(b) Two visible changes are that the blue solution becomes paler or colourless [1] and brown or pink copper forms, usually as a coating. [1] The magnesium strip becoming smaller is also acceptable.
(c) Magnesium is more reactive than copper, so it displaces copper from copper sulfate solution. [1] Gold is less reactive than copper, so it cannot displace copper ions. [1]
Gold and diamond
(a) Diamond has a giant covalent structure, or giant covalent lattice. [1]
(b) Each carbon atom forms strong covalent bonds [1] with other carbon atoms in a repeating network. [1]
(c) In gold, layers of atoms can slide over one another [1] while metallic bonding continues to hold the metal together. This makes gold malleable enough to form leaf. [1]
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