Acid and Base pH Indicators
The ranges for the color changes are given in the table below the figure, together with the corresponding pKa value of the indicators.
The molecule structure of each indicator is shown below the table.
See also pKa values of inorganic acids and bases, organic nitrogen compound and alcohols and carboxylic acids.
| Trade name | pH start | pH end | pKa | low pH color | high pH color |
| Cresol red - step 1 | 0.2 | 1.8 | 1.0 | red | yellow |
| Malachite green -step 1 | 0.2 | 1.8 | 1.3 | yellow | green |
| Thymol blue - step 1 | 1.2 | 2.8 | 1.7 | red | yellow |
| Methyl yellow | 2.9 | 4.0 | 3.3 | red | yellow |
| Methyl orange | 3.1 | 4.4 | 3.5 | red | yellow |
| Bromophenol blue | 3.0 | 4.6 | 4.1 | yellow | blue |
| Congo red | 3.0 | 5.0 | blue-violet | red | |
| Methyl orange in xylene cyanol (screened) | 3.2 | 4.2 | grey-violet | green | |
| Bromocresol green | 3.8 | 5.4 | 4.7 | yellow | blue |
| Methyl red | 4.4 | 6.2 | 5.1 | red | yellow |
| Methyl purple | 4.8 | 5.4 | purple | green | |
| Bromocresol purple | 5.2 | 6.8 | 6.4 | yellow | purple |
| Azolitmin (litmus) | 4.5 | 8.3 | red | blue | |
| Bromothymol blue | 6.0 | 7.6 | 7.3 | yellow | blue |
| Phenol red | 6.4 | 8.0 | 8.0 | yellow | red |
| Neutral red | 6.8 | 8.0 | red | yellow | |
| Cresol red -step 2 | 7.2 | 8.8 | 8.5 | yellow | reddish-purple |
| Naphtholphthalein | 7.3 | 8.7 | pale red | greenish-blue | |
| Thymol blue - step 2 | 8.0 | 9.6 | 9.2 | yellow | blue |
| Cresolphthalein | 8.2 | 9.8 | colorless | purple | |
| Phenolphthalein | 8.3 | 10.0 | 9.5 | colorless | red-pink |
| Thymolphthalein | 9.0 | 10.5 | 9.2 | colorless | blue |
| Alizarin yellow R | 10.1 | 12.0 | 11.2 | yellow | red |
| Indigo carmine | 11.4 | 13.0 | blue | yellow | |
| Malachite green -step 2 | 11.5 | 13.2 | green | colorless |
Related Topics
• Material Properties
Properties of gases, fluids and solids. Densities, specific heats, viscosities and more.
Related Documents
Acids - pH Values
pH values of acids like sulfuric, acetic and more..
Alcohols and Carboxylic Acids - Physical Data
Molweight, melting and boiling point, density, pKa-values, as well as number of carbon and hydrogen atoms in molecules are given for 150 different alcohols and acids.
Amines, Diamines and Cyclic Organic Nitrogen Compounds - pKa Values
Values for the negative logarithm of the acid dissociation constant, pKa, of the conjugated acid of amines, diamines and cyclic organic nitrogen compounds, shown together with the molecular structure of the acids.
Aqueous Salt Solutions - Acid and Base Properties
Salts contains ions that may affect the pH in aqueous solutions in both acidic and basic directions.
Bases - pH Values
pH values for bases like sodium hydroxide, ammonia and more.
Buffer Solutions
Definitions, explanations and examples of how to make buffer solutions.
Food and Foodstuff - pH Values
pH in common food products - like apples, butter, wines and more.
Inorganic Acids and Bases - pKa Values
Values for the negative logarithm of the acid dissociation constant, pKa, of inorganic acids and bases, as well as hydrated metal ions.
pH - Basic (alkaline) vs. Acidic
Introduction to pH - the acidic and basic (alkaline) definition.
pH in Human Biological Material
pH in human materials like blood, salvia and more.
Phenols, Alcohols and Carboxylic Acids - pKa Values
For oxygen containing organic compounds this is given: pKa (the negative logarithm of the acid dissociation constant), molecular structures, molar weights, density and melting and boiling points.
Strong and Weak Acids and Bases
The most common strong acids and bases, and some examples of weak acids and bases, together with definition of strong and weak acids and bases.
Sulfuric Acid - Density
Density of sulfuric acid at various temperatures and concentrations.