Methyl orange

Methyl orange is a pH indicator frequently used in titrations.

Additional recommended knowledge

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It is often chosen to be used in titrations because of its clear colour change. Because it changes colour at the pH of a mid-strength acid, it is usually used in titrations for acids. Unlike a universal indicator, methyl orange does not have a full spectrum of colour change, but has a sharper end point.

Indicator colours

In a solution becoming less acidic, methyl orange moves from red to orange and finally to yellow with the reverse occurring for a solution increasing in acidity. It should be noted that the entire colour change occurs in acidic conditions.

In an acid it is reddish and in alkali it is yellow.

Other Indicators

• Modified (or screened) methyl orange, an indicator consisting of a solution of methyl orange and xylene cyanol, changes from gray to green as the solution becomes more basic.
• A number of other common indicators are tabulated in the article on pH indicators.