Nitric acid is a strong acid and reacts in different ways like a oxidizing reagent, oxidizing acid and more with elements and compounds. It's reactions vary on concentration of the nitric acid solution. you will see lot of reactions of HNO3 in this tutorial.
You should be careful when you are using nitric acid because it is a very dangerous acid because it can cause harmful injuries to people.
As a typical acid, nitric acid can behave as oxidizing acid. These characteristics depends on the temperature and concentration of aqueous nitric acid solution.
Due to release of H+ ions in the water, nitric acid show acidic properties and have low pH values in aqueous solutions. So nitric acid can emit hydrogen gas with metals. But due to oxidizing acid characteristics, this typical acid - metal reaction can be different than other acid - metal reactions. In next sections of this tutorial, you will learn about these reactions of nitric acid.
2H+ + 2e → H2
Nitrogen is at +5 oxidation state in nitric acid, so nitrogen atom can be reduced to lower oxidation states and behave as a oxidizing agent.
Cu + HNO3 → Cu(NO3)2 + NO2 + H2O
Cu + HNO3 → Cu(NO3)2 + NO + H2O
Behavior as an oxidizing agent will depend on the concentration of nitric acid. (According to the concentration, give different products)
Nitric acid is an inorganic compound. But it also reacts with organic compounds.
Dilute nitric acid act as a typical acid when it reacts with a reactive metals such as sodium, magnesium, zinc and more. But nitric acid behaves differently (as an oxidizing acid) with less reactive metals such as copper, silver.
Dilute nitric acid reacts with magnesium and produce magnesium nitrate and hydrogen gas as the product.
Both dilute and concentrated nitric acid can behave as an oxidizing acid.
Dehydration is removing water, a simple explanation. Dinitrogen pentoxide (N2O5), is the anhydride of nitric acid, from which it can be prepared by dehydration of nitric acid at low temperatures.
Oxidation number of nitrogen is protected in this reaction.
Sulfur is oxidized into sulfuric acid (H2SO4) and nitric acid will be reduced to nitrogen dioxide (NO2). This reaction is an example to oxidizing ability of nitric acid.
Oxidation number of sulfur increases from 0 to +6 while nitrogen reduces from +5 to +4. Nitrogen dioxide is a brown colour gas you can see a brown colour gas is emitted from the reaction mixture. Sulfur is a yellow-white solid.
Sulfide ion is oxidized to sulfate ion. So the white precipitate, ZnS is disappeared when reaction is completed because ZnSO4 is soluble in water.
The mixture containing one volume of concentrated nitric acid and three volumes of concentrated hydrochloric acid is known as aqua regia. Even gold and platinum dissolve in aqua regia.
With copper, dilute nitric acid and concentrated nitric acid behave as an oxidizing acid.
According to the concentration of nitric acid, different products are given. If dilute nitric is used, nitric oxide (NO) is given. With concentrated nitric acid, nitrogen dioxide (NO2) is given. Copper is oxidized into copper(II) with both dilute or concentrated nitric acid and blue colour solution will be given in both occasions.
Copper is oxidized to copper +2 oxidation state while nitric acid is reduced to nitric oxide.
Copper is oxidized to copper +2 oxidation state while nitric acid is reduced to nitrogen dioxide (NO2).
Ag + HNO3 → AgNO3 + NO2 + H2O
Tin (Sn) and dilute nitric acid react to form Sn(NO3)2, NH4NO3 and water. Here tin is oxidized to its +2 oxidation state. Tin nitrate is soluble in water.
Lead(Pb) and dilute nitric acid react to form Lead nitrate ( Pb(NO3)2 ), NO2 and water. Here lead is oxidized to its +2 oxidation state. Lead nitrate is soluble in water.
Carbon (C) and hot concentrated nitric acid react to give carbon dioxide (CO2), nitrogen dioxide (NO2) and water. Here, carbon is oxidized to its +4 oxidation state and nitrogen's oxidation state is changed from +5 to +4.
Phosphorus reacts with nitric acid to give phosphoric acid (H3PO4), NO2 and H2O. This is a redox reaction. Oxidation number of phosphorous atom is increased from 0 to +5.
Silver reacts with nitric acid to give silver nitrate (AgNO3), NO2 and H2O. Silver is oxidized to +1 oxidation state.
HNO3 acid dissociate completely in the water and release hydronium ion (H3O+) in the water to form strong acid aqueous solution.
Sulfur and nitric oxide (NO) are given as the products by the reaction of hydrogen sulfide and nitric oxide. In the presence of excess nitric acid, given sulfur can be oxidized to sulfur dioxide furthermore.
In the laboratory, sometimes you can see brown colour in nitric acid bottles.
Nitric acid decomposes to nitrogen dioxide, oxygen gas and water when HNO3 acid solution is heated or exposed to sunlight.
QuestionsAsk your chemistry questions and find the answers
According to the some web resources in the internet, they says using HNO3 acid can make nitric oxide (NO) gas. Nitric oxide gas can be turned to nitrogen dioxide gas easily. Nitrogen dioxide is a toxic gas. This happnes because nitric acid is an oxidizing acid. But, HCl is not a oxidizng acid. So, no toxic gas forming when iron react with HCl acid.
Nitrogen - nitrogen is at +5 oxidation state. It is the maximum oxidation number shown by nitrogen. So nitrogen atom can be reduced to lower oxidation states.
Oxygen - Oxygen is at -2 oxidation state and can be oxidized to higher oxidation state.
Hydrogen - Hydrogen is at +1 oxidation state. So, it can be reduced to hydrogen gas.
Dilute nitric acid can behave as an oxidizing acid. But dilute sulfuric acid does not show properties of oxidizing acid.
When HNO3 reacts with silver or copper, nitrogen atom of nitric acid is reduced to nitric oxide (NO) or nitrogen dioxide. Also when magnesium is added to concentrated hot nitric acid, magnesium is oxidized while nitrogen atom of nitric acid is reduced. So reactions of HNO3 is not special for less reactive metals.