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Journal of Chemistry

Journal of Chemistry / 2019 / Article / Tab 3

Research Article

Natural Plant Extracts as Acid-Base Indicator and Determination of Their pKa Value

Table 3

Titration results of flower extracts and commercially available indicators.
IndicatorTitrand/titrantColour changeRequired volume of titrant
PhenolphthaleinNaOH/HClPink to colourless8.87 ± 0.0577
NH4OH/HClPink to colourless14.57 ± 0.0577
CH3COOH/NaOHColourless to pink12.07 ± 0.0577
sMethyl orangeNaOH/HClYellow to red9.17 ± 0.0577
NH4OH/HClYellow to red15.67 ± 0.1155
CH3COOH/NaOHRed to yellow5.27 ± 0.0577
Methyl redNaOH/HClYellow to red8.97 ± 0.0577
NH4OH/HClYellow to red16.13 ± 0.0577
CH3COOH/NaOHRed to yellow12.13 ± 0.0577
Bougainvillea glabraNaOH/HClBrownish yellow to red8.97 ± 0.0577
NH4OH/HClBrownish yellow to red15.17 ± 0.0577
CH3COOH/NaOHRed to brownish yellow12.23 ± 0.0577
Impatiens balsaminaNaOH/HClBrownish yellow to red9.07 ± 0.0577
NH4OH/HClBrownish yellow to red15.3 ± 0.1
CH3COOH/NaOHRed to brownish yellow12.13 ± 0.0577
Bauhinia purpureaNaOH/HClYellow to red8.93 ± 0.0577
NH4OH/HClYellow to red15.27 ± 0.0577
CH3COOH/NaOHRed to yellow12.3 ± 0.1