Question

What is the pH of carbon dioxide?

Answer 1

The pH is denoted as the ‘power of Hydrogen’ or ‘potential of hydrogen’. It is a scale measuring the acidity and the basicity of the liquids. Acidic solutions will have lower pH while basic solutions will have less pH.

Complete answer
The pH measures the range of acidity and basicity of a substance. The normal water is said to be having the normal pH with a pH of about 7. The pH scale is having a range from 0 to 14 on which less than 7 are said to be acidic while more than 7 are said to be basic. The relative amount of free hydrogen ions and free hydroxyl ions are measured with the help of the pH. The pH of carbon dioxide is around 5.6 since its dissolved gas is slightly acidic and when it is dissolved in water it remains naturally acidic. The reaction for the formation of carbonic acid from carbon dioxide when reacts with water is shown below:
${ CO }_{ 2 }+{ H }_{ 2 }O\xrightarrow { Sunlight\quad Energy } { CO }_{ 3 }+{ H }{ 2 }$
Both carbon dioxide and carbonic acid are slightly acidic in nature.

Additional information
-Carbon monoxide must dissolve in water to produce acid and then it would be acidic in nature and termed as acidic oxide.
-The reaction for the formation of carbon dioxide from carbon monoxide when reacts with water is shown below:
${ CO }+{ H }_{ 2 }O\xrightarrow { Sunlight\quad Energy } { CO }_{ 2 }+{ H }{ 2 }$
-For the reaction to occur in the case of gases when reacted with the base, the base taken must be hot and concentrated. Then only the gases will be acidic in nature.

Note:
The optimum pH for the normal oxygen is around 7. Thus oxygen is neutral, it is neither acidic nor basic. The optimum pH range for the nitrogen is around 3.6 to 7.2 when they are in the form of nitrogen fertilizers. It may be acidic or basic but mostly it is basic in nature.