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The diagram shows a hot water tank - HSC - SSCE Chemistry - Question 34 - 2011 - Paper 1
Question 34
The diagram shows a hot water tank. Name an appropriate material from which X can be made, and justify your choice. There are two common household methods to remov... show full transcript
Worked Solution & Example Answer:The diagram shows a hot water tank - HSC - SSCE Chemistry - Question 34 - 2011 - Paper 1
Step 1
Name an appropriate material from which X can be made, and justify your choice.
Answer
A suitable material for X is aluminum. Aluminum is preferred due to its higher reactivity compared to silver, which means it can effectively act as a sacrificial anode in the hot water tank. In this setup, the aluminum will oxidize preferentially, protecting the silver components from corrosion. This reaction can be represented as:
ightarrow ext{2Al(OH)}_3 + ext{3H}^+$$ This demonstrates that aluminum’s oxidation potential is favorable in preventing corrosion of less reactive metals like silver.Step 2
Explain, with the use of equations, the chemistry involved in the aluminium tray method.
Answer
In the aluminium tray method, the tarnish on silver is removed by an electrochemical reaction. When silver cutlery is placed in an aluminium tray with a sodium hydrogen carbonate solution, a galvanic cell is formed. Aluminum acts as a sacrificial anode. The overall reaction can be simplified as follows:
- Aluminum oxidizes:
ightarrow ext{2Al}^{3+} + ext{6e}^-$$
- Silver ions are reduced:
ightarrow ext{Ag}$$
This means that the aluminum gives up electrons, which the silver ions use to reduce back to metallic silver, thus restoring its shine.
Step 3