Question

A silvery-white metal on treatment with $NaOH$ and $HCl$ liberates \[{{H}_{2}}\] gas to form B and C respectively. The metal A will not react with acid D due to that formation of a passive film on the surface. Hence, it is used for transporting acid D. Identify A, B, C, D and support your answer with balanced equations.

Answer 1

Hint: The answer here is based on the fact that the silvery - white metal does not mean it is silver but the one metal which is able to react with both acid as well as base and this reaction gives you the required answer.

Complete step by step answer:
In our chemistry classes, we are familiar with the metals and its occurrence in nature in various forms and also about the colour of the compounds.
- Here, let us know which metal acts with both acid and base.
- Aluminium is silvery white metal and this is the one that reacts with both acids and bases. Thus, it is an unusual metal and in the presence of strong acids the metal dissolves with the liberation of hydrogen to form salts.
- The reaction is as shown,
\[2Al+6HCl\to 2AlC{{l}_{3}}+3{{H}_{2}}\uparrow \]
With the bases aluminium produces hydroxides with the evolution of hydrogen gas and the reaction is as shown,
\[2Al+2NaOH+6{{H}_{2}}O\to 2N{{a}^{+}}+2{{[Al{{(OH)}_{4}}]}^{-}}+3{{H}_{2}}\uparrow \]
- Aluminium forms the passive film on the surface when it is reacted with nitric acid, that is the layer of aluminium oxide is formed when aluminium comes in contact with air and when nitric acid is added to the metal there is no reaction with the acid.
- It is for this reason that aluminium containers are used for the transportation of nitric acid.
Therefore, the correct answer is that the compound A =$Al$ , compound B = \[Na[Al(O{{H}_{4}})]\] , compound C = $AlC{{l}_{3}}$ and compound D will be $HN{{O}_{3}}$.

Note: Note that passive film is nothing but the spontaneous formation of ultra thin film of corrosion product on the surface of the metal which acts as a barrier to the additional chemical reaction and this film is helpful in mitigating corrosion damage.