[{"data":1,"prerenderedAt":86},["ShallowReactive",2],{"reference-colligative-constants":3},{"table":4},{"id":5,"slug":6,"title":7,"shortTitle":8,"category":9,"description":10,"metaDescription":11,"columns":12,"rows":27,"entryCount":66,"source":67,"notes":69,"relatedTopics":75,"relatedElements":77,"seoKeywords":78},14,"colligative-constants","Boiling-Point Elevation and Freezing-Point Depression Constants","Kb / Kf (molal)","Solutions","Molal boiling-point-elevation (Kb) and freezing-point-depression (Kf) constants for common solvents. Use ΔTb = i·Kb·m and ΔTf = i·Kf·m, where m is the molality of the solution and i is the van 't Hoff factor.","Molal Kb and Kf constants for water, benzene, chloroform, ethanol, camphor, and more — the boiling-point-elevation and freezing-point-depression reference for colligative-property calculations.",[13,17,21,24],{"key":14,"label":15,"type":16},"solvent","Solvent","text",{"key":18,"label":19,"type":20},"formula","Formula","chem",{"key":22,"label":23,"type":16},"Kb","Kb (bp elevation)",{"key":25,"label":26,"type":16},"Kf","Kf (fp depression)",[28,33,38,43,48,53,58,62],{"solvent":29,"formula":30,"Kb":31,"Kf":32},"Water","H₂O","0.512 °C·kg/mol","1.86 °C·kg/mol",{"solvent":34,"formula":35,"Kb":36,"Kf":37},"Acetic acid","CH₃COOH","3.07 °C·kg/mol","3.9 °C·kg/mol",{"solvent":39,"formula":40,"Kb":41,"Kf":42},"Benzene","C₆H₆","2.53 °C·kg/mol","5.12 °C·kg/mol",{"solvent":44,"formula":45,"Kb":46,"Kf":47},"Chloroform","CHCl₃","3.63 °C·kg/mol","4.68 °C·kg/mol",{"solvent":49,"formula":50,"Kb":51,"Kf":52},"Nitrobenzene","C₆H₅NO₂","5.24 °C·kg/mol","8.1 °C·kg/mol",{"solvent":54,"formula":55,"Kb":56,"Kf":57},"Ethanol","C₂H₅OH","1.20 °C·kg/mol","—",{"solvent":59,"formula":60,"Kb":61,"Kf":57},"Carbon disulfide","CS₂","2.34 °C·kg/mol",{"solvent":63,"formula":64,"Kb":57,"Kf":65},"Camphor","C₁₀H₁₆O","37.7 °C·kg/mol",8,{"label":68},"ChemWhiz course-canonical colligative constants (from the Topic 19 course rules)",[70,71,72,73,74],"ΔTb = i·Kb·m raises the boiling point; ΔTf = i·Kf·m lowers the freezing point. Both use MOLALITY (mol solute per kg solvent), not molarity.","The van 't Hoff factor i counts dissolved particles: i = 1 for nonelectrolytes, i ≈ the ion count for strong electrolytes (e.g. i ≈ 2 for NaCl, i ≈ 3 for CaCl₂).","A dash means that constant is not used in this course for that solvent.","Camphor's very large Kf made it the classic solvent for molar-mass determination by freezing-point depression (the Rast method).","These are the course-canonical values: every ChemWhiz colligative problem uses the constants in this table.",[76],"colligative-properties",[],[79,80,81,82,83,84,85],"boiling point elevation constant","freezing point depression constant","molal Kb Kf table","ebullioscopic constant","cryoscopic constant","colligative properties","van t Hoff factor",1785108608465]