{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"ph"},"result":{"entity_type":"calculator","id":"ph","calculator_id":"ph","canonical_url":"https://tttkmbb.com/chemistry/ph","name":"pH Calculator","title":"pH Calculator – pH, pOH and H⁺/OH⁻ Concentrations of a Strong Acid or Base Solution","category":"chemistry","category_name":"Chemistry","tool_name":"calculate_ph","featured_mcp_tool":false,"description":"Converts between pH, pOH, hydrogen-ion concentration and hydroxide-ion concentration at 25 °C (Kw = 1.0×10⁻¹⁴) from any one of them, and classifies the solution as acidic, neutral or basic.","use_when":"You know one of pH, pOH, [H⁺] or [OH⁻] for an aqueous solution (for example the concentration of a fully dissociated strong acid or base) and need the others.","do_not_use_when":"The solution contains a weak acid or base or a buffer, where [H⁺] is not equal to the nominal concentration (use henderson-hasselbalch for buffers), or the temperature differs a lot from 25 °C.","inputs":[{"name":"h_concentration_mol_per_l","label":"[H⁺] concentration","type":"number","unit":"mol/L","required":false,"max":100,"exclusive_min":0,"description":"Hydrogen-ion (hydronium) concentration, e.g. the molarity of a strong monoprotic acid such as HCl.","example":0.001},{"name":"oh_concentration_mol_per_l","label":"[OH⁻] concentration","type":"number","unit":"mol/L","required":false,"max":100,"exclusive_min":0,"description":"Hydroxide-ion concentration, e.g. the molarity of NaOH. Used when [H⁺] is not given."},{"name":"ph","label":"pH","type":"number","required":false,"min":-2,"max":16,"description":"Known pH; when given it takes precedence over the other inputs."},{"name":"poh","label":"pOH","type":"number","required":false,"min":-2,"max":16,"description":"Known pOH; used when pH is not given."}],"outputs":[{"name":"ph","label":"pH","type":"number","decimals":3,"description":"−log10[H⁺]."},{"name":"poh","label":"pOH","type":"number","decimals":3,"description":"−log10[OH⁻] = 14 − pH at 25 °C."},{"name":"h_concentration_mol_per_l","label":"[H⁺]","type":"number","unit":"mol/L","decimals":15,"description":"Hydrogen-ion concentration = 10^(−pH)."},{"name":"oh_concentration_mol_per_l","label":"[OH⁻]","type":"number","unit":"mol/L","decimals":15,"description":"Hydroxide-ion concentration = 10^(−pOH) = Kw / [H⁺]."},{"name":"h_concentration_scientific","label":"[H⁺] (scientific)","type":"string","decimals":4,"description":"[H⁺] in scientific notation, mol/L."},{"name":"oh_concentration_scientific","label":"[OH⁻] (scientific)","type":"string","decimals":4,"description":"[OH⁻] in scientific notation, mol/L."},{"name":"classification","label":"Classification","type":"string","decimals":4,"description":"Acidic (pH < 7), Neutral (pH = 7) or Basic (pH > 7) at 25 °C."}],"input_schema":{"type":"object","properties":{"h_concentration_mol_per_l":{"description":"Hydrogen-ion (hydronium) concentration, e.g. the molarity of a strong monoprotic acid such as HCl. Unit: mol/L.","type":"number","maximum":100,"exclusiveMinimum":0,"examples":[0.001],"x-unit":"mol/L"},"oh_concentration_mol_per_l":{"description":"Hydroxide-ion concentration, e.g. the molarity of NaOH. Used when [H⁺] is not given. Unit: mol/L.","type":"number","maximum":100,"exclusiveMinimum":0,"x-unit":"mol/L"},"ph":{"description":"Known pH; when given it takes precedence over the other inputs.","type":"number","minimum":-2,"maximum":16},"poh":{"description":"Known pOH; used when pH is not given.","type":"number","minimum":-2,"maximum":16}},"additionalProperties":false},"output_schema":{"type":"object","properties":{"ph":{"description":"−log10[H⁺].","type":"number"},"poh":{"description":"−log10[OH⁻] = 14 − pH at 25 °C.","type":"number"},"h_concentration_mol_per_l":{"description":"Hydrogen-ion concentration = 10^(−pH). Unit: mol/L.","type":"number","x-unit":"mol/L"},"oh_concentration_mol_per_l":{"description":"Hydroxide-ion concentration = 10^(−pOH) = Kw / [H⁺]. Unit: mol/L.","type":"number","x-unit":"mol/L"},"h_concentration_scientific":{"description":"[H⁺] in scientific notation, mol/L.","type":"string"},"oh_concentration_scientific":{"description":"[OH⁻] in scientific notation, mol/L.","type":"string"},"classification":{"description":"Acidic (pH < 7), Neutral (pH = 7) or Basic (pH > 7) at 25 °C.","type":"string"}}},"formula":"pH = −log10[H⁺]; pOH = −log10[OH⁻]; pH + pOH = pKw = 14.00 at 25 °C; [H⁺] × [OH⁻] = Kw = 1.0×10⁻¹⁴","method":"Assumes an aqueous solution at 25 °C and that a strong acid or base is completely dissociated, so [H⁺] (or [OH⁻]) equals its nominal molarity; activity effects at high concentration and the autoionisation contribution below about 10⁻⁶ mol/L are ignored.","sources":[{"name":"OpenStax Chemistry 2e – 14.2 pH and pOH","url":"https://openstax.org/books/chemistry-2e/pages/14-2-ph-and-poh","type":"textbook","retrieved_at":"2026-09-23"},{"name":"Wikipedia – pH","url":"https://en.wikipedia.org/wiki/PH","type":"reference","retrieved_at":"2026-09-23"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"0.001 M HCl","inputs":{"h_concentration_mol_per_l":0.001},"expected":{"ph":3,"poh":11,"oh_concentration_mol_per_l":1e-11,"h_concentration_scientific":"1.000e-3","classification":"Acidic"},"url":"https://tttkmbb.com/api/v1/calculate/ph?h_concentration_mol_per_l=0.001"},{"name":"pH 8.5 solution","inputs":{"ph":8.5},"expected":{"poh":5.5,"h_concentration_mol_per_l":3.1623e-9,"oh_concentration_mol_per_l":0.0000031623,"h_concentration_scientific":"3.162e-9","classification":"Basic (alkaline)"},"url":"https://tttkmbb.com/api/v1/calculate/ph?ph=8.5"}],"faq":[{"q":"Why is the pH of a 10⁻⁸ M HCl solution not 8?","a":"Below about 10⁻⁶ mol/L the H⁺ from water's autoionisation matters and the real pH stays just under 7; this calculator ignores that contribution and reports the formal value."},{"q":"Does the neutral point change with temperature?","a":"Yes. Kw rises with temperature, so neutral water has pH 7.00 only at 25 °C (about 6.63 at 50 °C); all results here use pKw = 14.00."}],"tags":["ph","poh","hydrogen ion concentration","hydroxide concentration","acid base","strong acid ph"],"related":[{"calculator_id":"henderson-hasselbalch","reason":"pH of a buffer from pKa and the acid/base ratio."},{"calculator_id":"molarity","reason":"Get the acid or base molarity that sets [H⁺] or [OH⁻]."},{"calculator_id":"logarithm","reason":"General log10 calculations."}],"links":{"html":"https://tttkmbb.com/chemistry/ph","markdown":"https://tttkmbb.com/chemistry/ph.md","json":"https://tttkmbb.com/chemistry/ph.json","api":"https://tttkmbb.com/api/v1/calculate/ph","schema":"https://tttkmbb.com/api/v1/calculators/ph","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-23"},"timestamp":"2026-09-23T23:23:58Z","next_actions":[{"tool":"run_calculator","calculator_id":"ph","reason":"Run pH Calculator with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/chemistry/ph.md"}}