Question

Explain the following processes.
(i) Nitric acid can be transported in an aluminium container.
(ii) A mixture of dilute sodium hydroxide and aluminium pieces is used to open drains.
(iii) Graphite is used as a lubricant.
(iv) Diamond is used as an abrasive.
(v) Aluminium alloys are used to make the aircraft body.
(vi) Aluminium utensils should not be kept in water overnight.
(vii) Aluminium wire is used to make transmission cables.

Answer 1

Hint: Aluminium has many important chemical and physical properties like high reactivity, ductility, malleability, and conductivity. These properties have been exploited in different phenomena influencing our day to day life and various industrial processes.

Complete step by step answer:
(i) Concentrated nitric acid can be transported in aluminium containers safely. This is because the reaction between concentrated nitric acid and aluminium leads to the formation of aluminium oxide. The layer of the oxide formed inside the container acts as a protective layer and allows safe transport of nitric acid.
(ii) Aluminium reacts with alkalis (or bases) like sodium hydroxide to release hydrogen gas. The hydrogen gas evolved in the reaction accumulates at the reaction sites and exerts pressure which leads to the opening of the blocked drains.
(iii) The structure of graphite is in the form of sheets. These sheets are attached to each other by weak Van der Waals forces which allow them to slip over each other. Thus when applied between two surfaces these graphite sheets allow movement without their wear and tear. Hence, the graphite can be used as a lubricant.
(iv) Diamond is the hardest material in the world. Thus, it can be rubbed against other surfaces to give the required shape and can be used as abrasive.
(v) Aluminium alloys are light in weight and have high tensile strength. They are highly ductile and malleable, so most suitable to be used in aircraft bodies.
(vi) Aluminium is very reactive in nature. It reacts with oxygen in the presence of moisture or water to form its oxide and harmful aluminium ions. So, it can be harmful to keep water in the aluminium utensils for a long time.
(vii) Aluminium has both good conductivity and high ductility. Hence, it is very suitable to make transmission wires.

Note: The diamond and graphite are both the allotropes of carbon as they are made of carbon elements. Aluminium is the most abundant metal which is found in the earth crust and shows many properties that makes it usable in human day to day life. One can explain the major property and some specifics of that element which can elaborate the reason given for each sentence of chemical processes.