[{"data":1,"prerenderedAt":101},["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":30,"entryCount":68,"sources":69,"notes":77,"relatedTopics":82,"relatedElements":86,"seoKeywords":87,"relatedReferences":95,"tableTitle":98,"tableDescription":99,"seoTitle":100},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 full transition interval lies inside the steep region of the titration curve.","Acid-base indicator table with pKa values, pH color-change ranges, colors, and the indicator-selection rule for titrations.",[13,17,21,24,27],{"key":14,"label":15,"type":16},"indicator","Indicator","text",{"key":18,"label":19,"type":16,"sortType":20},"pka","pKa","numeric",{"key":22,"label":23,"type":16},"range","pH Range",{"key":25,"label":26,"type":16},"acid","Acid Color",{"key":28,"label":29,"type":16},"base","Base Color",[31,37,42,46,50,54,58,64],{"indicator":32,"pka":33,"range":34,"acid":35,"base":36},"Methyl orange","3.7","3.1 to 4.4","Red","Yellow",{"indicator":38,"pka":39,"range":40,"acid":36,"base":41},"Bromocresol green","4.7","3.8 to 5.4","Blue",{"indicator":43,"pka":44,"range":45,"acid":35,"base":36},"Methyl red","5.1","4.4 to 6.2",{"indicator":47,"pka":48,"range":49,"acid":35,"base":41},"Litmus","6.5","4.5 to 8.3",{"indicator":51,"pka":52,"range":53,"acid":36,"base":41},"Bromothymol blue","7.1","6.0 to 7.6",{"indicator":55,"pka":56,"range":57,"acid":36,"base":35},"Phenol red","7.9","6.4 to 8.0",{"indicator":59,"pka":60,"range":61,"acid":62,"base":63},"Phenolphthalein","9.4","8.3 to 10.0","Colorless","Purple-pink",{"indicator":65,"pka":66,"range":67,"acid":36,"base":35},"Alizarin yellow R","11.0","10.2 to 12.0",8,[70,73],{"label":71,"covers":72},"ChemWhiz-curated pKa values","the pKa column",{"label":74,"url":75,"covers":76},"Wikipedia, pH indicator","https://en.wikipedia.org/wiki/PH_indicator","color ranges and colors",[78,79,80,81],"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: place the indicator's full color-change interval inside the steep region of the titration curve. Weak acid + strong base: phenolphthalein. Weak base + strong acid: methyl red or bromocresol green are close matches, while methyl orange can work when its transition remains inside the steep drop. Strong + strong: 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, making it 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.",[83,84,85],"solution-stoichiometry-and-titrations","acids-bases-and-ph","buffers-and-titration-curves",[],[88,89,90,91,92,93,94],"acid base indicator table","pH indicator colors","phenolphthalein pH range","methyl orange color change","indicator pKa table","choosing titration indicator","bromothymol blue range",[96,97],"titration-curves","weak-acid-base-constants","Indicator Color Ranges and pKa","Choose an indicator whose transition range brackets the equivalence-point pH of your titration.","Acid-Base Indicators and pKa",1787246032889]