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B (i) Name the ore from which aluminium is extracted - Leaving Cert Chemistry - Question B - 2008
Question B
B (i) Name the ore from which aluminium is extracted. What substance is used to convert this ore into a soluble aluminium compound in the first stage of the extracti... show full transcript
Worked Solution & Example Answer:B (i) Name the ore from which aluminium is extracted - Leaving Cert Chemistry - Question B - 2008
Step 1
i) Name the ore from which aluminium is extracted. What substance is used to convert this ore into a soluble aluminium compound in the first stage of the extraction?
Answer
The ore from which aluminium is extracted is called bauxite. To convert bauxite into a soluble aluminium compound, sodium hydroxide (also known as caustic soda, NaOH) is used. This process results in the formation of sodium aluminate.
Step 2
ii) Write balanced equations for the reactions taking place at the positive and negative electrodes in the electrolysis of alumina.
Answer
During the electrolysis of alumina (Al2O3), the following reactions occur:
At the positive electrode (anode):
ightarrow ext{O}_2 + 4e^-$$ At the negative electrode (cathode): $$ ext{Al}^{3+} + 3e^- ightarrow ext{Al}$$ These equations describe how oxygen is produced at the anode and aluminium is produced at the cathode.Step 3
iii) What is the function of cryolite (Na3AlF6) in the electrolysis of alumina?
Answer
Cryolite serves multiple purposes in the electrolysis of alumina. It lowers the melting point of alumina, allowing it to dissolve more readily, which increases conductivity and helps reduce energy costs during the electrolysis process.
Step 4
iv) Why is recycling of aluminium metal important for the protection of the environment?
Answer
Recycling aluminium is vital for several reasons: it saves energy compared to producing new aluminium, reduces waste and litter associated with aluminium products, prevents the depletion of natural resources, and helps in conserving the environment by lowering greenhouse gas emissions. It is a more economical and sustainable approach.