a(i) Write the chemical formula of alumina.
I. to obtain alumina from Bauxite
II. as solvent for alumina.
(iii) Name the electrodes used in the extraction of aluminium.
I. name the substance liberated at the anode;
II. write the equation for the reaction that leads to decrease in the size of the anode.
a(i) The chemical formula for alumina,(aluminium oxide) is Al\(_2\)O\(_3\)
(ii) In the extraction of aluminium,the compound that is used;
I. to obtain alumina from Bauxite - Sodium hydroxide, NaOH
II. as solvent for alumina - Cryolite, Na\(_3\)AlF\(_6\)
(iii) The electrodes used in the extraction of aluminium are
- cathode (negative electrode) graphite,
- anode (positive electrode) carbon rods or slabs.
(iv)The extraction of aluminium is expensive due to the high energy requirements of the electrolysis process, which involves purifying bauxite, melting aluminium oxide, and using electricity to break down electrolytes.
(v) In the extraction of aluminium:
I. the substance liberated at the anode is oxygen gas (O₂)
II. the equation for the reaction that leads to decrease in the size of the anode is: C + O\(_2\) → CO\(_2\)
b(i) Ions that cause hardness of water are Ca\(^{2+}\) and Mg\(^{2+}\)
(ii) Advantages of hard water
- strengthening bones and teeth,
- potentially aiding digestion, and
- reducing the risk of cardiovascular disease.
- improves the taste of water due to the presence of the ions.
Disadvantages of hard water
- skin and hair dryness,
- reduced soap effectiveness,
- potential appliance damage, and plumbing issues.
c(i) Destructive distillation of coal is a process of heating coal in the absence of air (or with limited oxygen) to break down its complex molecules into simpler, useful products like coke, coal gas, coal tar, and ammoniacal liquor.
(ii) products obtained from the destructive distillation of coal are:
- coke
- coal gas
- coal tar and
- ammoniacal liquor
d(i) Gases which can be used to demonstrate the fountain experiment are;
- Ammonia, NH\(_3\)
- Hydrogen chloride gas, HCl
(ii) Ammonia (NH\(_3\)) and hydrogen chloride (HCl) are used in the fountain experiment to demonstrate the high solubility of gases in water. When water is introduced into a flask containing either gas, the gas dissolves rapidly, creating a pressure drop that forces water upwards, forming a "fountain".
