Acidic Gases Examples and List | Gaseous Acids

Acidic gases form acidic solutions when they dissolve in water. As an example, when nitrogen dioxide dissolve in water, nitric acid and nitrous acid mixture is given. In this tutorial, we are going to learn, what are the acidic gases and how they behave and form acidic solutions in water.

nitrogen dioxide and water reaction

List of acidic gases

These acidic gases dissolve in water and form acidic solution. But, every gas does not dissolve in water in same amount and dissolved gases dissociate in different amounts to form the acidic solution. As an example, chlorine gas dissolve in water than bromine does. Also chorine gas dissociate than bromine gas to give acids.

  • Carbon dioxide
  • Dinitrogen trioxide
  • Nitrogen dioxide
  • Dinitrogen tetroxide
  • Fluorine
  • Chlorine
  • Bromine
  • Sulfur dioxide
  • Sulfur trioxide
  • Dichlorine monoxide

Importance and effects of acidic gases

Acidic gases are important to prepare different compounds such as production of nitric acid from nitrogen dioxide by ostwald process. Also, some acidic gases such as sulfur dioxide, nitrogen dioxide cause to acid rains which is a major environmental pollution incident in the world.

How acidic gases form acidic solutions in water?

Most times (not always), when acidic gas dissolve in water, a weak acidic solution form. In following examples, you may understand this very well. Lets take carbon dioxide gas as an example. First gas dissolve in water to be in the aqueous phase.

CO2(aq) + H2O(l) → H2CO3(aq)

But, like nitrogen dioxide gases can form strong acidic solutions because nitrogen dioxide make nitric acid in water. Those kind of gases are introduced as strong acidic gases.

Acidic gases formed by different elements

It is good to categorize acidic gases according to the elements. Therefore you can find which element can make acidic gases.

Acidic gases formed by carbon

Carbon dioxide (CO2) is the only acidic gas formed by carbon. When carbon dioxide dissolve in water, carbonic acid (H2CO3), a weak acid is given as the product.

Remember, acidity of carbon dioxide gas is not enough to form acid rains.

Acidic gases of nitrogen

Nitrogen form so many oxides. From them, oxides above +3 oxidation number of nitrogen, are acidic. So, dinitrogen trioxide, nitrogen dioxide, dinitrogen tetroxide and dinitrogen pentoxide are acidic. But, these gases form different acids when they dissolve in water.

Dinitrogen trioxide (N2O3)

Nitrous acid is given as the acid. Oxidation number of nitrogen is protected in this reaction.

N2O3(aq) + H2O(l) → HNO2(aq)

Nitrogen dioxide (NO2)

Nitrous acid and nitric acid are given as the acids. Nitric acid is a strong acid. Due to formation of nitric acid, acidic rains can be occurred. So nitrogen dioxide is a gas which can cause acid rains.

2NO2(aq) + H2O(l) → HNO2(aq) + HNO3(aq)

Nitrous acid is not stable and decomposes to nitric acid, nitric oxide and water. Then, above reaction can be written as below. In this reaction, nitrogen dioxide reacts with water and produce nitric acid and nitric oxide.

3NO2(aq) + H2O(l) → NO(aq) + 2HNO3(aq)

Acidic gases formed by sulfur element

Sulfur dioxide (SO2) and sulfur trioxide (SO3) are acidic gases of sulfur. These acidic gases of sulfur can cause acid rains.

Sulfur dioxide (SO2)

Sulfur dioxide forms sulfurous acid (H2SO3) in the water.

SO2(aq) + H2O(l) → H2SO3(aq)

Sulfur trioxide (SO3)

Sulfur dioxide forms sulfuric acid in the water. Which is a strong acid and dibasic acid in the chemistry.

SO3(aq) + H2O(l) → H2SO4(aq)

Hydrogen sulfide

Hydrogen sulfide (H2S) is a very toxic and an acidic gas. Solubility of hydrogen sulfide is very low and also it is a weak acid. Acidity of hydrogen sulfide is less than sulfurous acid and sulfuric acid.

Fluorine gas

When fluorine gas is sent to water, hydrogen fluoride (HF) is formed. Hydrogen fluoride is a weak acid. Products of fluorine and water reaction depend on how much fluorine gas is sent to the water.

When fluorine is sent to water slowly, oxygen is produced.

2F2 + 2H2O → 4HF + O2

When excess fluorine is sent to water fast

3F2 + 3H2O → 6HF + O3

Chlorine gas

When chlorine gas dissolve in water, hypochlorous acid (HOCl) and hydrochloric acid (HCl) are produced.

Cl2(aq) + H2O(l) → HCl(aq) + HCl(aq)

HOCl is a weak acid and HCl acid is a strong acid.


Is carbon monoxide an acidic gas?

Carbon monoxide is a neutral gas.

Give 10 acidic gases examples with their molecular formulas?

  • Carbon dioxide - CO2
  • Dinitrogen trioxide - N2O3
  • Nitrogen dioxide - NO2
  • Chlorine - Cl2
  • Hydrogen sulfide - H2S
  • Sulfur dioxide - SO2
  • Sulfur trioxide - SO3

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