Question

Select the correct option.
Conc. $HN{O_3}$

a.) React with $Al$ to form aluminium nitrate.
b.) React with aluminium vigorously
c.) Doesn’t react with $Al$ .
d.) React with platinum.

Answer 1

Hint: In order to deal with this question first we will elaborate this given compound then we will proceed further by using the property of the given compound and will see its reaction with aluminium and platinum in order to get the correct answer out of the given options.

Complete step by step answer:
Nitric acid ($HN{O_3}$) , is commonly referred to by the other name aqua fortis and scientific name spirit of niter, nitric acid is highly corrosive amongst mineral acids. The pure compound is colorless, but older samples tend to get a yellow cast because of the decomposition into nitrogen and water oxides.
Let us see the reaction of nitric acid or $HN{O_3}$ with aluminium.
Due to the thin and reactive protective layer of aluminum oxide formed on the metal surface due to the reaction of aluminum metal with air oxygen, aluminum metal is not attacked by nitric acid of any concentration.
 $HN{O_3} + Al \to {\text{No reaction}}$

We get down deeper to this reaction and know what happens. If we are using dilute nitric acid then aluminum will react with it and give aluminum nitrate. That’s why it’s always important to look at the concentration of components. On the other hand, when we use concentrated nitric acid instead of dilute nitric acid, this case will lead to totally different results. As we have shown in the above reaction. Concentrated nitric acid (more than 60% of composition) is a power oxidizing agent. Due to this property it creates a thin layer of Aluminum oxide around the surface of aluminum. This layer will prevent Aluminum to undergo for further reaction. That’s why in the end of the reaction, we don’t get any compounds. Hence, Conc. $HN{O_3}$ doesn’t react with $Al$ .
So, the correct answer is “Option C”.

Note: Nitric acid is made by reaction of nitrogen dioxide with water. The nitric oxide formed by the reaction is usually reoxidized by the oxygen in the air to create additional nitrogen dioxide. Most nitric acid commercially available has a water concentration of 68 per cent. Nitric acid is used for producing ammonium nitrate for fertilizers, making plastics, and making dyes. This also helps to produce bombs such as nitroglycerin and TNT.