pH Calculator

pH Calculator - Solution Acidity Calculator

🧪 Calculate pH, pOH, hydrogen ion concentration, and hydroxide ion concentration. Perfect for chemistry students, laboratory work, pool maintenance, and aquarium care.

What is pH?

pH is a measure of how acidic or basic (alkaline) a solution is. It ranges from 0 to 14, with 7 being neutral. pH below 7 is acidic, above 7 is basic. The "p" stands for "power" and H for hydrogen ion concentration.

pH Scale Explained

• 0-3: Strongly acidic (battery acid, stomach acid)
• 4-6: Weakly acidic (tomatoes, coffee, rain water)
• 7: Neutral (pure water)
• 8-10: Weakly basic (sea water, baking soda)
• 11-14: Strongly basic (ammonia, bleach, drain cleaner)

pH Formulas

pH = -log₁₀[H⁺] - Negative logarithm of hydrogen ion concentration

pOH = -log₁₀[OH⁻] - Negative logarithm of hydroxide ion concentration

pH + pOH = 14 - At 25°C (standard temperature)

[H⁺] × [OH⁻] = 1.0×10⁻¹⁴ - Water ion product constant (Kw)

Applications of pH

• Swimming Pools: Maintain pH 7.2-7.8 for comfort and chlorine effectiveness
• Aquariums: Most fish thrive at pH 6.5-8.0
• Agriculture: Soil pH affects nutrient availability
• Food Processing: Control microbial growth
• Medicine: Blood pH must stay 7.35-7.45
• Cosmetics: Skin pH is typically 4.5-5.5

pH in Daily Life

• Stomach acid: pH 1.5-3.5 (digests food)
• Lemon juice: pH 2 (citric acid)
• Coffee: pH 5 (slightly acidic)
• Human blood: pH 7.4 (slightly basic)
• Soap: pH 9-10 (removes oils)
• Bleach: pH 12-13 (disinfects)

How to Measure pH

• pH paper/strips: Color change indicates pH range
• pH meter: Electronic device for precise measurement
• pH indicators: Chemicals that change color (litmus, phenolphthalein)
• Universal indicator: Shows full pH range with different colors

💡 Did You Know? The pH scale is logarithmic, meaning each whole number change represents a 10-fold change in acidity. A solution with pH 3 is 10× more acidic than pH 4, and 100× more acidic than pH 5!