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Corrosion of an iron pipe can be prevented by connecting it to a magnesium bar buried in the ground - VCE - SSCE Chemistry - Question 14 - 2009 - Paper 1
Question 14
Corrosion of an iron pipe can be prevented by connecting it to a magnesium bar buried in the ground. The magnesium corrodes in preference to the iron. If the averag... show full transcript
Worked Solution & Example Answer:Corrosion of an iron pipe can be prevented by connecting it to a magnesium bar buried in the ground - VCE - SSCE Chemistry - Question 14 - 2009 - Paper 1
Step 1
Step 2
Convert Charge to Moles of Magnesium
Answer
Next, we use Faraday's law, which states that 1 mole of electrons carries a charge of approximately 96500 C. The reaction for magnesium corrosion requires 2 moles of electrons (2e⁻) per mole of magnesium reacting:
ext{Moles of Mg} = rac{Q}{2 imes F} ext{, where } F = 96500 ext{ C/mol}.Substituting the values:
ext{Moles of Mg} = rac{2.0 imes 10^{-6} ext{ C}}{2 imes 96500 ext{ C/mol}} \ = rac{2.0 imes 10^{-6}}{193000} \ ext{Moles of Mg} ext{ (reacting per second) } ext{ is approximately } 1.0 imes 10^{-11} ext{ mol.}