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pH Formula:
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pH is a measure of the acidity or basicity of a solution. It is defined as the negative logarithm (base 10) of the hydrogen ion concentration. The pH scale ranges from 0 to 14, with lower values indicating acidity, higher values indicating basicity, and 7 being neutral.
The calculator uses the pH formula:
Where:
Explanation: The formula calculates pH by taking the negative base-10 logarithm of the hydrogen ion concentration. This mathematical operation converts the wide range of hydrogen ion concentrations into a more manageable scale from 0 to 14.
Details: pH measurement is crucial in various fields including chemistry, biology, medicine, environmental science, and industry. It helps determine the acidity or alkalinity of solutions, which affects chemical reactions, biological processes, and material properties.
Tips: Enter the hydrogen ion concentration in mol/L. The value must be greater than 0. For accurate results, use scientific notation for very small concentrations (e.g., 1.0e-7 for neutral water).
Q1: What is the pH of pure water?
A: Pure water at 25°C has a hydrogen ion concentration of 1.0 × 10⁻⁷ mol/L, giving it a pH of 7.0, which is neutral.
Q2: How does temperature affect pH?
A: Temperature affects the dissociation of water, changing the hydrogen ion concentration. The pH of pure water decreases slightly as temperature increases, though it remains neutral.
Q3: What is the relationship between pH and pOH?
A: pH and pOH are related by the equation: pH + pOH = 14 at 25°C. This relationship comes from the ion product of water (Kw = [H⁺][OH⁻] = 1.0 × 10⁻¹⁴).
Q4: Can pH be negative or greater than 14?
A: Yes, for very concentrated strong acids, pH can be negative, and for very concentrated strong bases, pH can be greater than 14. However, these are extreme cases not commonly encountered.
Q5: Why use logarithmic scale for pH?
A: The logarithmic scale compresses the wide range of hydrogen ion concentrations (from about 10⁰ to 10⁻¹⁴ mol/L) into a more manageable scale of 0-14, making it easier to work with and compare different solutions.