Show that non-metallic oxides are acidic in nature

Our Objective

Show that non-metallic oxides are acidic in nature.


The Theory

A non-metal is a chemical element that lacks the majority of metallic qualities in chemistry; they range from colourless gases (such as hydrogen) to glossy and high melting point solids (like boron). Non-metal electrons act differently than metal electrons. Non-metals, with a few exceptions, are set in place, resulting in nonmetals being poor conductors of heat and electricity and brittle or crumbly when solid. Metals' electrons are often free moving, which is why they are strong conductors and can be easily flattened into sheets and dragged into wires. Non-metal atoms are moderate to strongly electronegative, attracting electrons in chemical processes and forming acidic compounds. 

Most non-metals have biological, technical, or household roles or applications. Living beings are a combination of non-metals such as hydrogen, oxygen, carbon, and nitrogen. Almost every non-metal application has a specific medicine and pharmaceuticals, lighting and lasers, and domestic products. 

While the word "non-metallic" has been used since at least 1566, there is no universally accepted technical definition of a non-metal. Some elements exhibit a distinct blend of metallic and non-metallic characteristics; which of these borderline situations is classified as non-metal depends on the categorisation criteria. As seen in the accompanying periodic table extract, fourteen elements are effectively always recognised as non-metals, and up to around nine more are regularly sometimes added.

It is well known that elements at the extreme left of the periodic table readily mix with oxygen to create the most basic oxides, while those at the extreme right generate the most acidic oxides.

The transition element oxides in the centre are either amphoteric or neutral. Amphoteric oxides have both acidic and basic characteristics (they react with bases and acids). Neutral oxides, however, have neither acidic nor basic characteristics. Non-metals react with oxygen to form non-metal oxides. Non-metal oxides are acidic in nature. 

                                                                                    Non-Metal + Oxygen → Non-Metal Oxide

Thus, non-metals react with oxygen to form acidic oxides. The acidic non-metal oxides turn blue litmus to red. Non-metal oxides are often acidic in nature. When sulphur burns in the air, it reacts with oxygen to form sulphur dioxide, an acidic oxide. When sulphur oxide is dissolved in water, it produces an acid known as sulphurous (H2SO3) acid. In aqueous solutions, non-metallic oxides create stable anions. If anions are stable, they are ready to emit hydrogen ions. When non-metallic oxides dissociate in water, an acidic solution is formed. As a result, non-metallic oxides are acidic. 

                                                                                                      SO+ H2O → H2SO3 

Carbonic acid is formed when carbon dioxide combines with water. The following is the reaction: 

                                                                                                      CO+ H2O ↔ H2CO3

When water and the atmosphere are in chemical equilibrium, carbon dioxide interacts to generate carbonic acid. This is also crucial in the chemical weathering of rocks. Rainwater is typically in chemical balance with the environment, making it acidic. 


Learning Outcomes

  • Students learn the concept of metal and non-metals.  
  • They will learn about the acidic and basic nature of metals and non-metals.  
  • They will acquire basic laboratory skills.