|Preferred IUPAC name
3D model (JSmol)
|Molar mass||327.33 g·mol−1|
|Density||1.28 g/cm3, solid|
|Melting point||>300 °C (572 °F; 573 K)|
not precisely defined
|0.5 g/100 mL (20 °C)|
|Solubility||insoluble in diethyl ether|
|Main hazards||Toxic (T)|
|GHS signal word||Danger|
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|60 mg/kg (rat, oral)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Methyl orange is a pH indicator frequently used in titration because of its clear and distinct colour variance at different pH values. Methyl orange shows pink colour in acidic medium and yellow colour in basic medium. Because it changes colour at the pH of a mid strength acid, it is usually used in titration for acids. Unlike a universal indicator, methyl orange does not have a full spectrum of colour change, but it has a sharp end point.
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. The entire color change occurs in acidic conditions.
|Methyl orange (pH indicator)|
|below pH 3.1||above pH 4.4|
In an acid, it is reddish and in alkali, it is yellow. Methyl orange has a pKa of 3.47 in water at 25 °C (77 °F).
|Methyl orange in xylene cyanol solution (pH indicator)|
|below pH 3.2||above pH 4.2|
Modified (or screened) methyl orange, an indicator consisting of a solution of methyl orange and xylene cyanol, changes from grey-violet to green as the solution becomes more basic.
|Wikimedia Commons has media related to Methyl orange.|