Understanding pH and Pure Water
Pure water is a unique substance in terms of its acidity and basicity. It serves as a fundamental reference point for understanding pH.
pH Scale Explanation
- The pH scale ranges from 0 to 14, where:
- 0-6 indicates acidity
- 7 is neutral
- 8-14 indicates basicity
- A pH of 7 means pure water has equal concentrations of hydrogen ions (H+) and hydroxide ions (OH-), rendering it neutral.
Assertion: Pure Water's Neutrality
- Pure water is neither acidic nor basic because:
- It contains an equal number of H+ and OH- ions.
- This balance prevents any shift towards acidity or basicity.
Reason: pH and Hydrogen Ion Concentration
- The pH of a solution is inversely proportional to the concentration of hydrogen ions:
- As H+ concentration increases, pH decreases, indicating acidity.
- Conversely, as H+ concentration decreases, pH increases, indicating basicity.
- Therefore, in pure water, the concentration of H+ ions is 1 x 10^-7 moles per liter, resulting in a pH of 7.
Conclusion
- The assertion that pure water is neither acidic nor basic is accurate.
- The reason provided about the relationship between pH and H+ concentration further supports this assertion.
Understanding these concepts is crucial for grasping how different substances interact in aqueous solutions, especially in contexts like environmental science and analytical chemistry.