Characteristics Of Acidic Oxides

Oxides are compounds (of course they must be pure). Its composition contains only two elements, one of which must be oxygen element, if the other is a metal element, it is called a metal oxide; if the other is not a metal element, it is called a non-metal oxide.
 
Acid oxide
 
We know that bases react with acids to form salt and water, and bases react with certain non-metal oxides to form salt and water.
E.g:
2NaOH+CO₂=Na₂CO₃+H₂O
Ca(OH)₂+SO3=CaSO4+H₂O
The above reaction shows that carbon dioxide and sulfur trioxide have similar properties to acids. Therefore, people call carbon dioxide and sulfur trioxide such as oxides that can react with alkalis and only produce salt and water, which are called acidic oxides.
Most non-metal oxides are acidic oxides, such as CO₂, SO₂ and so on.
The acidic oxide is not necessarily a non-metal oxide (such as Mn2O7).

 
With water
Most acidic oxides can directly combine with water to form acid.
E.g:
CO₂+H₂O=H₂CO₃
SO3+H2O=H2SO4
SiO2 cannot directly react with water to generate H2SiO3.
Unstable acids can also be decomposed by heat to form acidic oxides.
E.g:
H2CO3=(heating)CO2↑+H2O
H2SO4=(heating)SO3↑+H2O
Here carbon dioxide and sulfur trioxide can be regarded as the products after the dehydration of carbonic acid and sulfuric acid, called acid anhydrides.
It can be said that acidic oxides are all acid anhydrides.
 
With alkali
Acidic oxides can react with alkalis to produce salt and water.
 
With alkaline oxide
Under certain conditions, alkaline oxides and acidic oxides react to form salts.
E.g:
CaO+CO2=CaCO3
CaO+SiO2=(high temperature)CaSiO3