Why Do Chemists Use Methyl Orange in a Titration?

By Staff WriterLast Updated Mar 25, 2020 8:42:55 PM ET

Methyl orange is frequently used as an indicator in acid titrations because it very clearly changes from red at a pH of 3.1 to orange at a pH of 4.4. Because the change in color takes place around the pH of most acids, methyl orange is commonly used for strong acid titrations and not for base titrations.

Titration is a technique in chemistry that is used to find a concentration of an unknown solution. Different pH indicators are used in titration that change color at a certain pH, allowing the chemist to know when a reaction has been completed. Among these indicators are universal indicators, phenolphthalein and methyl orange.

Methyl orange, which is also used as a textile dye, is used as an indicator in titration because of its bright and distinct color change. At a pH value of 3.1, methyl orange appears red. When the pH rises to 4.4, methyl orange changes to a bright orange color. While phenolphthalein is used for base titrations and some acid titrations, and universal indicators have a full spectrum of color changes, methyl orange is used specifically for acid titrations because it has a very clear and sharp color change with a definitive endpoint. Proper safety equipment should be used when dealing with methyl orange, as it can damage and cause mutations to DNA.