Non-Metallic Oxides: An Introduction
All non-metals combine with oxygen to generate covalent oxides, which then react with water to create acids or use bases to create salts. Most non-metal oxides are acidic in nature, and when they combine to create oxy acids, they produce hydronium ions (H3O+) in an aqueous medium. The actions of acidic oxides can be categorised in two broad terms. Initially, oxides where the non-metal displays one of its typical oxidation values, such as sulphur trioxide (SO3) as well as dinitrogen pentoxide (N2O5), are referred to as acid anhydrides.
Base has a harsh flavour and a soapy texture to it. A base tends to turn red litmus paper into blue. Bases include components such as potassium hydroxide (caustic potash), sodium hydroxide (caustic soda), sodium carbonate (washing soda), calcium hydroxide, lime (calcium oxide), and so on. Non-metallic oxides do not dissolve in water, while in a basic aqueous solution, it readily dissolves to generate salt.
Reaction of Non-Metallic Oxide with Base
Non-metal oxides are naturally acidic. Carbon dioxide, for instance, is a non-metal oxide. Carbonic acid is formed whenever carbon dioxide is dissolved in water.
Hence, whenever a reaction of non-metallic oxide with base occurs, both reactants neutralise one another, producing salt and water as a by-product.
The general equation of the reaction of non-metallic oxide with base is:
\[Non - Metallic~Oxide + Base \to Salt + Water\]
Reaction of Non-Metallic Oxide with Base Examples
The reaction of non-metallic oxide with base examples is explained using certain chemical equations below.
With Sodium Hydroxide (NaOH) Base
The non-metallic oxide carbon dioxide (CO2) reacts with base sodium hydroxide (NaOH), and as a result, a salt sodium carbonate (Na2CO3) and water is produced.
\[2NaOH\left( {aq} \right) + C{O_2}\left( g \right) \to N{a_2}C{O_3}\left( {aq} \right) + {H_2}O\left( l \right)\]
This process demonstrates that non-metal oxides like carbon dioxide (CO2) are acidic.
With Calcium Hydroxide Ca(OH)2 Base
The non-metallic oxide carbon dioxide (CO2) reacts with base calcium hydroxide Ca(OH)2 and as a result, salt calcium carbonate (CaCO3) and water are produced.
\[Ca{\left( {OH} \right)_2}\left( {aq} \right) + C{O_2}\left( g \right) \to CaC{O_3}\left( {aq} \right) + {H_2}O\left( l \right)\]
This process demonstrates that non-metal oxides like carbon dioxide (CO2) are acidic.
With Magnesium Hydroxide Mg(OH)2 Base
The non-metallic oxide carbon dioxide (CO2) reacts with base magnesium hydroxide Mg(OH)2 and as a result salt magnesium carbonate (MgCO3) and water is produced.
\[Mg{\left( {OH} \right)_2}\left( {aq} \right) + C{O_2}\left( g \right) \to MgC{O_3}\left( {aq} \right) + {H_2}O\left( l \right)\]
This process demonstrates that non-metal oxides like carbon dioxide (CO2) are acidic.
With Potassium Hydroxide (KOH) Base
The non-metallic oxide sulphur dioxide (SO2) reacts with base potassium hydroxide (KOH) and as a result, salt potassium sulphate (K2SO3) and water is produced.
\[2KOH\left( {aq} \right) + S{O_2}\left( g \right) \to {K_2}S{O_3}\left( {aq} \right) + {H_2}O\left( l \right)\]
This process demonstrates that non-metal oxides like sulphur dioxide (SO2) are acidic.
Characteristics of Non-Metallic Oxides of Sulphur and Nitrogen in Atmosphere
Oxides in the atmosphere have the potential to interact with water to produce acid rain. Water reacts with non-metal oxides like sulphur dioxide (SO2) and nitrogen oxide (NO2). These oxides can break down in the water to create acid, which then rains down as acid rain on the land. Consequently, this acid rain leads to damage to buildings and rocks and hazards to wildlife. Sulphur can easily react with atmospheric air to form sulphur dioxide.
Interesting Facts
The p-block is dominated by non-metals. They produce a wide range of oxide compounds.
Acidic oxides are generally referred to as non-metallic oxides.
When non-metallic oxides and water interact, acids are produced. Non-metallic oxides are acidic, and when SO3 is combined with water, for example, the resulting mixture of H2SO4 is extremely acidic.
Metallic oxides with base possess very low melting and boiling point, and even while molten, they do not conduct electricity.
Sulphur and phosphorus are highly soluble in water and form acidic oxides and so they are neutralized with base to form salts.
Key Features
Non-metallic oxides react with base to produce corresponding salt and water proving that non-metallic oxides are acidic in nature.
The general equation of reaction of non-metallic oxides with base denotes Non-metallic oxide + base = salt + water.
Bases which can react with non-metallic acids are potassium hydroxide (caustic potash), sodium carbonate (washing soda), lime (calcium oxide), sodium hydroxide (caustic soda), calcium hydroxide, and so on.
Non-metallic oxides are covalent compounds because they exchange particles with oxygen atoms to create oxide molecules.
FAQs on Reaction of Non-Metallic Oxide with Base
1. What is the general outcome when a non-metallic oxide reacts with a base?
When a non-metallic oxide reacts with a base, it undergoes a neutralization reaction to form salt and water. This occurs because most non-metallic oxides are acidic in nature. The reaction is conceptually similar to a classic acid-base reaction. For a deeper understanding, you can explore the reaction of non-metallic oxide with base in more detail.
2. Can you provide the chemical equation for the reaction of carbon dioxide with calcium hydroxide?
Yes, the reaction between carbon dioxide (a non-metallic oxide) and calcium hydroxide (a base) is a classic example. The balanced chemical equation is:
CO₂(g) + Ca(OH)₂(aq) → CaCO₃(s) + H₂O(l)
In this reaction, carbon dioxide gas is passed through limewater (calcium hydroxide solution), producing a white precipitate of calcium carbonate (salt) and water. This reaction is often used as a test for carbon dioxide.
3. Why are non-metallic oxides generally considered acidic oxides?
Non-metallic oxides are called acidic oxides because they react with water to form acids. For instance, carbon dioxide (CO₂) dissolves in water to form carbonic acid (H₂CO₃), and sulphur dioxide (SO₂) forms sulphurous acid (H₂SO₃). These acids then increase the concentration of hydrogen ions (H⁺) in the solution, which is the defining characteristic of an acid. This acidic nature is why they readily react with bases to form salt and water, as explained in the study of nonmetal oxides.
4. What is the difference between the reaction of a metallic oxide with an acid and a non-metallic oxide with a base?
The primary difference lies in the chemical nature of the oxides:
- Metallic oxides (like MgO, CuO) are generally basic in nature. Therefore, they react with acids to form salt and water. Example: MgO + 2HCl → MgCl₂ + H₂O.
- Non-metallic oxides (like CO₂, SO₂) are generally acidic in nature. Therefore, they react with bases to form salt and water. Example: CO₂ + 2NaOH → Na₂CO₃ + H₂O.
Both are types of neutralization reactions, but they involve opposite pairings of acidic/basic reactants. You can compare this with the reaction of metallic oxides with acids.
5. Are all non-metallic oxides acidic? Provide examples.
No, not all non-metallic oxides are acidic. While most are, some are neutral. Neutral oxides do not react with either acids or bases. Common examples of neutral non-metallic oxides include:
- Carbon monoxide (CO)
- Nitrous oxide (N₂O)
- Nitric oxide (NO)
These oxides are an important exception to the general rule that non-metal oxides are acidic.
6. How does the reaction of a non-metallic oxide with a base relate to the concept of neutralization?
This reaction is a perfect example of neutralization because an acidic substance (the non-metallic oxide) reacts with a basic substance (the base) to produce a neutral salt and water. It demonstrates that the definition of an acid isn't limited to substances like HCl or H₂SO₄ but also includes acidic oxides which produce acids in aqueous solution. This concept is a key part of the CBSE Class 10 chapter on Acids, Bases and Salts.
7. What products are formed when sulphur dioxide (SO₂) reacts with sodium hydroxide (NaOH)?
When sulphur dioxide (SO₂), an acidic non-metallic oxide, reacts with sodium hydroxide (NaOH), a strong base, they neutralize each other to form the salt sodium sulphite (Na₂SO₃) and water (H₂O). The balanced chemical equation for this reaction is:
SO₂(g) + 2NaOH(aq) → Na₂SO₃(aq) + H₂O(l)
8. What real-world importance does the reaction between non-metallic oxides and bases have?
This reaction is crucial in controlling industrial pollution. Acidic non-metallic oxides like sulphur dioxide (SO₂) and nitrogen oxides (NOₓ) are major air pollutants that cause acid rain. In industrial scrubbers, these harmful acidic gases are passed through a spray of a basic substance, like calcium carbonate (limestone) or calcium hydroxide (slaked lime). The base neutralizes the acidic oxides, converting them into harmless salts and preventing their release into the atmosphere.
