[{"data":1,"prerenderedAt":238},["ShallowReactive",2],{"reference-weak-acid-base-constants":3},{"table":4},{"id":5,"slug":6,"title":7,"shortTitle":8,"category":9,"description":10,"metaDescription":11,"columns":12,"rows":36,"entryCount":194,"sources":195,"notes":204,"relatedTopics":210,"relatedElements":216,"seoKeywords":217,"relatedReferences":225,"tableTitle":229,"tableDescription":230,"seoTitle":231,"filters":232},12,"weak-acid-base-constants","Ka and Kb Values for Weak Acids and Bases","Ka / Kb Constants","equilibrium","Acid-ionization (Ka) and base-ionization (Kb) constants at 25 °C for the weak acids, weak bases, and conjugate pairs used throughout the acid-base, buffer, hydrolysis, and titration topics. Use Ka × Kb = Kw = 1.0 × 10⁻¹⁴ to convert between a conjugate pair.","Ka, pKa, Kb, and pKb for common weak acids and bases at 25 °C, for equilibrium, ICE-table, and hydrolysis calculations.",[13,17,21,24,27,30,32,34],{"key":14,"label":15,"type":16},"formula","Formula","chem",{"key":18,"label":19,"type":20},"name","Name","text",{"key":22,"label":23,"type":20},"type","Type",{"key":25,"label":26,"type":16},"step","Ionization Step",{"key":28,"label":28,"type":16,"sortType":29},"Ka","numeric",{"key":31,"label":31,"type":20,"sortType":29},"pKa",{"key":33,"label":33,"type":16,"sortType":29},"Kb",{"key":35,"label":35,"type":20,"sortType":29},"pKb",[37,45,51,58,64,70,76,82,88,94,99,105,111,116,121,127,134,140,145,150,155,159,164,169,174,179,184,189],{"formula":38,"name":39,"type":40,"step":41,"family":42,"Ka":43,"pKa":44,"Kb":41,"pKb":41},"CH₃COOH","Acetic acid","Weak acid","—","Acetic acid / acetate","1.8 × 10⁻⁵","4.76",{"formula":46,"name":47,"type":40,"step":41,"family":48,"Ka":49,"pKa":50,"Kb":41,"pKb":41},"C₆H₅COOH","Benzoic acid","Benzoic acid / benzoate","6.5 × 10⁻⁵","4.19",{"formula":52,"name":53,"type":40,"step":54,"family":55,"Ka":56,"pKa":57,"Kb":41,"pKb":41},"HCO₃⁻","Bicarbonate ion","Ka₂","Carbonic acid / bicarbonate","4.68 × 10⁻¹¹","10.33",{"formula":59,"name":60,"type":40,"step":61,"family":55,"Ka":62,"pKa":63,"Kb":41,"pKb":41},"H₂CO₃","Carbonic acid","Ka₁","4.27 × 10⁻⁷","6.37",{"formula":65,"name":66,"type":40,"step":41,"family":67,"Ka":68,"pKa":69,"Kb":41,"pKb":41},"HCNO","Cyanic acid","Cyanic acid / cyanate","3.47 × 10⁻⁴","3.46",{"formula":71,"name":72,"type":40,"step":54,"family":73,"Ka":74,"pKa":75,"Kb":41,"pKb":41},"H₂PO₄⁻","Dihydrogen phosphate ion","Phosphoric acid ladder","6.17 × 10⁻⁸","7.21",{"formula":77,"name":78,"type":40,"step":41,"family":79,"Ka":80,"pKa":81,"Kb":41,"pKb":41},"FCH₂COOH","Fluoroacetic acid","Fluoroacetic acid / fluoroacetate","2.57 × 10⁻³","2.59",{"formula":83,"name":84,"type":40,"step":41,"family":85,"Ka":86,"pKa":87,"Kb":41,"pKb":41},"HCOOH","Formic acid","Formic acid / formate","1.77 × 10⁻⁴","3.75",{"formula":89,"name":90,"type":40,"step":41,"family":91,"Ka":92,"pKa":93,"Kb":41,"pKb":41},"HCN","Hydrocyanic acid","Hydrocyanic acid / cyanide","4.9 × 10⁻¹⁰","9.31",{"formula":95,"name":96,"type":40,"step":41,"family":96,"Ka":97,"pKa":98,"Kb":41,"pKb":41},"HF","Hydrofluoric acid","7.2 × 10⁻⁴","3.14",{"formula":100,"name":101,"type":40,"step":102,"family":73,"Ka":103,"pKa":104,"Kb":41,"pKb":41},"HPO₄²⁻","Hydrogen phosphate ion","Ka₃","2.14 × 10⁻¹³","12.67",{"formula":106,"name":107,"type":40,"step":41,"family":108,"Ka":109,"pKa":110,"Kb":41,"pKb":41},"HOCl","Hypochlorous acid","Hypochlorous acid / hypochlorite","3.5 × 10⁻⁸","7.46",{"formula":112,"name":113,"type":40,"step":41,"family":114,"Ka":115,"pKa":98,"Kb":41,"pKb":41},"HNO₂","Nitrous acid","Nitrous acid / nitrite","7.24 × 10⁻⁴",{"formula":117,"name":118,"type":40,"step":61,"family":73,"Ka":119,"pKa":120,"Kb":41,"pKb":41},"H₃PO₄","Phosphoric acid","7.59 × 10⁻³","2.12",{"formula":122,"name":123,"type":124,"step":61,"family":123,"Ka":125,"pKa":126,"Kb":41,"pKb":41},"C₆H₈O₇","Citric acid","Polyprotic weak acid","7.41 × 10⁻⁴","3.13",{"formula":128,"name":129,"type":130,"step":41,"family":131,"Ka":132,"pKa":133,"Kb":41,"pKb":41},"NH₄⁺","Ammonium ion","Conjugate acid","Ammonia / ammonium","5.56 × 10⁻¹⁰","9.25",{"formula":135,"name":136,"type":130,"step":41,"family":137,"Ka":138,"pKa":139,"Kb":41,"pKb":41},"CH₃NH₃⁺","Methylammonium ion","Methylamine / methylammonium","2.27 × 10⁻¹¹","10.64",{"formula":141,"name":142,"type":143,"step":41,"family":131,"Ka":41,"pKa":41,"Kb":43,"pKb":144},"NH₃","Ammonia","Weak base","4.74",{"formula":146,"name":147,"type":143,"step":41,"family":147,"Ka":41,"pKa":41,"Kb":148,"pKb":149},"(CH₃)₂NH","Dimethylamine","5.4 × 10⁻⁴","3.27",{"formula":151,"name":152,"type":143,"step":41,"family":137,"Ka":41,"pKa":41,"Kb":153,"pKb":154},"CH₃NH₂","Methylamine","4.4 × 10⁻⁴","3.36",{"formula":156,"name":157,"type":158,"step":41,"family":42,"Ka":41,"pKa":41,"Kb":132,"pKb":133},"CH₃COO⁻","Acetate ion","Conjugate base",{"formula":160,"name":161,"type":158,"step":41,"family":48,"Ka":41,"pKa":41,"Kb":162,"pKb":163},"C₆H₅COO⁻","Benzoate ion","1.54 × 10⁻¹⁰","9.81",{"formula":165,"name":166,"type":158,"step":41,"family":67,"Ka":41,"pKa":41,"Kb":167,"pKb":168},"CNO⁻","Cyanate ion","2.88 × 10⁻¹¹","10.54",{"formula":170,"name":171,"type":158,"step":41,"family":91,"Ka":41,"pKa":41,"Kb":172,"pKb":173},"CN⁻","Cyanide ion","2.04 × 10⁻⁵","4.69",{"formula":175,"name":176,"type":158,"step":41,"family":79,"Ka":41,"pKa":41,"Kb":177,"pKb":178},"FCH₂COO⁻","Fluoroacetate ion","3.89 × 10⁻¹²","11.41",{"formula":180,"name":181,"type":158,"step":41,"family":85,"Ka":41,"pKa":41,"Kb":182,"pKb":183},"HCOO⁻","Formate ion","5.65 × 10⁻¹¹","10.25",{"formula":185,"name":186,"type":158,"step":41,"family":108,"Ka":41,"pKa":41,"Kb":187,"pKb":188},"ClO⁻","Hypochlorite ion","2.86 × 10⁻⁷","6.54",{"formula":190,"name":191,"type":158,"step":41,"family":114,"Ka":41,"pKa":41,"Kb":192,"pKb":193},"NO₂⁻","Nitrite ion","1.38 × 10⁻¹¹","10.86",28,[196,200],{"label":197,"url":198,"covers":199},"ChemWhiz-curated weak-acid Ka values at 25 °C, consistent with OpenStax Chemistry 2e, Appendix H (Ionization Constants of Weak Acids)","https://openstax.org/books/chemistry-2e/pages/h-ionization-constants-of-weak-acids","the weak acids and their conjugate bases",{"label":201,"url":202,"covers":203},"ChemWhiz-curated weak-base Kb values at 25 °C, consistent with OpenStax Chemistry 2e, Appendix I (Ionization Constants of Weak Bases)","https://openstax.org/books/chemistry-2e/pages/i-ionization-constants-of-weak-bases","the weak bases and their conjugate acids",[205,206,207,208,209],"All values at 25 °C (298.15 K). A dash means the constant is not tabulated for that species; derive it from the conjugate partner with Ka × Kb = Kw.","For a conjugate pair, pKa + pKb = pKw ≈ 14.00 at 25 °C (tabulated pairs may differ in the last digit from independent rounding).","Larger Ka (smaller pKa) = stronger weak acid; larger Kb (smaller pKb) = stronger weak base. A polyprotic acid loses each proton in turn with Ka1 > Ka2 > Ka3.","The Ionization Step column marks the successive protons of a polyprotic acid (phosphoric acid gives Ka1, Ka2, Ka3; carbonic acid gives Ka1, Ka2). Filter by Conjugate family to select a specific pair or ladder (acetic acid with acetate, or the full phosphoric-acid ladder), or by Type to group all weak acids, weak bases, and conjugates.","ChemWhiz uses this one consistent value set across the site.",[211,212,213,214,215],"acids-bases-and-ph","buffers-and-titration-curves","solubility-and-complex-ion-equilibria","chemical-equilibrium","entropy-and-free-energy",[],[218,219,220,221,222,223,224],"Ka values table","Kb values table","acid ionization constant","base ionization constant","pKa table","weak acid strength","conjugate acid base pair",[226,227,228],"strong-acids-bases","acid-base-indicators","titration-curves","Weak-Acid Ka and Weak-Base Kb at 25 °C","A smaller Ka or Kb means a weaker acid or base; each ionization step of a polyprotic acid has its own Ka.","Ka and Kb for Weak Acids and Bases",[233,234],{"key":22,"label":23},{"key":235,"label":236,"options":237},"family","Conjugate family",[42,48,55,67,73,79,85,91,108,114,131,137],1787246032640]