3 This question is about the extraction of metals.
Element R is extracted from its oxide by reduction with hydrogen.
The equation for the reaction is:
3 H2 + RO3 → R + 3 H2O
3-1 The sum of the relative formula masses (Mr) of the reactants (3 H2 + RO3) is 150. Calculate the relative atomic mass (Ar) of R.
Relative atomic masses (Ar): H = 1 O = 16 [2 marks]
ANSWER
3-2 Identify element R.
You should use:
Your answer to question 03.1
The periodic table.
Identity of R = __________ [1 mark]
ANSWER
Identity of R = Molybdenum (Mo)
3-3 Carbon is used to extract tin (Sn) from tin oxide (SnO2). The equation for the reaction is:
SnO2 + C → Sn + CO2
Calculate the percentage atom economy for extracting tin in this reaction.
Relative atomic masses (Ar): C = 12 O = 16 Sn = 119
[3 marks]
ANSWER
3-4 Tungsten (W) is a metal.
Tungsten is extracted from tungsten oxide (WO3)
All other solid products from the extraction method must be separated from the tungsten.
Table 2 shows information about three possible methods to extract tungsten from tungsten oxide.
Table 2
3-5 Evaluate the three possible methods for extracting tungsten from tungsten oxide. [4 marks]
ANSWER
From the table, it is clear that carbon and iron are the cheapest reactants, whereas hydrogen is the most expensive reactant;
Also, separating solid products is expensive and time consuming,
Method 1: tungsten needs to be separated from tungsten carbide and some tungsten is lost as tungsten carbide along with carbon dioxide produced will also escape;
Method 2: the water vapour produced will escape but no separation of solids is needed
Method 3: tungsten needs to be separated from iron oxide.
