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pH Formula:
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pH is a measure of the acidity or basicity of an aqueous solution. It is defined as the negative logarithm (base 10) of the hydrogen ion concentration. At 25°C, the pH scale ranges from 0 to 14, with 7 being neutral.
The calculator uses the pH formula:
Where:
Note: At 25°C, the ion product of water \( K_w = 10^{-14} \), which defines the relationship between [H⁺] and [OH⁻] concentrations.
Details: pH measurement is crucial in various fields including chemistry, biology, medicine, environmental science, and industrial processes. It helps determine the acidity or basicity of solutions and is essential for many chemical reactions and biological processes.
Tips: Enter the hydrogen ion concentration in mol/L. The value must be greater than 0. The calculator will compute the corresponding pH value at 25°C.
Q1: What is the relationship between pH and pOH?
A: At 25°C, pH + pOH = 14, where pOH = -log[OH⁻]. This relationship comes from the water dissociation constant \( K_w = [H^+][OH^-] = 10^{-14} \).
Q2: What are typical pH values for common substances?
A: Battery acid: ~0, Lemon juice: ~2, Pure water: 7, Baking soda: ~8.5, Ammonia: ~11, Bleach: ~13.
Q3: Why is temperature important in pH calculations?
A: The dissociation constant of water (K_w) changes with temperature, which affects the pH scale. The relationship pH + pOH = 14 is only valid at 25°C.
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 exceed 14, though such measurements require special techniques.
Q5: How accurate is pH calculation from [H⁺] concentration?
A: The calculation is mathematically exact, but actual pH measurements may be affected by ionic strength, temperature, and other factors that influence hydrogen ion activity.