[{"data":1,"prerenderedAt":90},["ShallowReactive",2],{"reference-acid-base-indicators":3},{"table":4},{"id":5,"slug":6,"title":7,"shortTitle":8,"category":9,"description":10,"metaDescription":11,"columns":12,"rows":29,"entryCount":67,"source":68,"notes":72,"relatedTopics":77,"relatedElements":81,"seoKeywords":82},18,"acid-base-indicators","Acid-Base Indicators: Color Ranges and pKa Values","Indicators","Acids & Bases","The common acid-base indicators with their pKa values, color-change intervals, and acid/base colors. Choose an indicator whose pKa is within about 1 pH unit of the titration's equivalence-point pH — the color change then lands on the steep rise of the titration curve.","Acid-base indicator table: pKa values, pH color-change ranges, and colors for methyl orange, phenolphthalein, bromothymol blue, and more — with the indicator-selection rule for titrations.",[13,17,20,23,26],{"key":14,"label":15,"type":16},"indicator","Indicator","text",{"key":18,"label":19,"type":16},"pka","pKa",{"key":21,"label":22,"type":16},"range","pH Range",{"key":24,"label":25,"type":16},"acid","Acid Color",{"key":27,"label":28,"type":16},"base","Base Color",[30,36,41,45,49,53,57,63],{"indicator":31,"pka":32,"range":33,"acid":34,"base":35},"Methyl orange","3.7","3.1 to 4.4","Red","Yellow",{"indicator":37,"pka":38,"range":39,"acid":35,"base":40},"Bromocresol green","4.7","3.8 to 5.4","Blue",{"indicator":42,"pka":43,"range":44,"acid":34,"base":35},"Methyl red","5.1","4.4 to 6.2",{"indicator":46,"pka":47,"range":48,"acid":34,"base":40},"Litmus","6.5","4.5 to 8.3",{"indicator":50,"pka":51,"range":52,"acid":35,"base":40},"Bromothymol blue","7.1","6.0 to 7.6",{"indicator":54,"pka":55,"range":56,"acid":35,"base":34},"Phenol red","7.9","6.4 to 8.0",{"indicator":58,"pka":59,"range":60,"acid":61,"base":62},"Phenolphthalein","9.4","8.3 to 10.0","Colorless","Purple-pink",{"indicator":64,"pka":65,"range":66,"acid":35,"base":34},"Alizarin yellow R","11.0","10.2 to 12.0",8,{"label":69,"url":70,"license":71},"pKa values: ChemWhiz course-canonical (Topic 23). Color ranges and colors: Wikipedia, pH indicator (CC BY-SA 4.0)","https://en.wikipedia.org/wiki/PH_indicator","CC BY-SA 4.0",[73,74,75,76],"An indicator is itself a weak acid, HIn ⇌ H⁺ + In⁻, whose acid and base forms have different colors. The eye sees the color change over roughly pKa ± 1 (the [HIn]/[In⁻] ratio swinging from about 10:1 to 1:10).","Selection rule: match pKa(indicator) to the equivalence-point pH. Weak acid + strong base (equivalence pH 8 to 10): phenolphthalein. Weak base + strong acid (equivalence pH 4 to 6): methyl red or bromocresol green. Strong + strong (equivalence pH 7): almost any indicator on this table works, because the curve is nearly vertical through pH 3 to 11.","Methyl orange changes color well before the equivalence point of a weak-acid titration — the classic wrong-indicator example.","Phenolphthalein's listed transition is its first (colorless to pink, pH 8.3 to 10.0); it fades again in very strongly basic solution.",[78,79,80],"solution-stoichiometry-and-titrations","acids-bases-and-ph","buffers-and-titration-curves",[],[83,84,85,86,87,88,89],"acid base indicator table","pH indicator colors","phenolphthalein pH range","methyl orange color change","indicator pKa table","choosing titration indicator","bromothymol blue range",1785108608498]