The pH of pure water is generally neutral, around 7, which means that it is neither acidic nor basic. This is because pure water contains an equal number of hydrogen ions (H+) and hydroxide ions (OH-). The concentration of these ions determines the pH of a substance.
In pure water, the concentration of hydrogen ions is equal to the concentration of hydroxide ions, resulting in a neutral pH. However, it is important to note that the pH of water can be affected by various factors, such as the presence of impurities or dissolved gases.
For example, water that contains a high concentration of dissolved carbon dioxide gas (CO2) can become slightly acidic due to the formation of carbonic acid (H2CO3). This can occur when water comes into contact with carbon dioxide in the air or when it is used to extinguish a fire. Similarly, water that contains a high concentration of dissolved minerals can become slightly basic due to the presence of alkaline substances.