Methyl Orange

Chemical properties

Orange-yellow powder. Soluble in hotwater; insoluble in alcohol.

The Uses of Methyl Orange

Methyl orange is a pH indicator frequently used in titrations, also used for histological microscopy.

The Uses of Methyl Orange

As indicator in 0.1% aqueous solution. pH: 3.1 red, 4.4 yellow. Employed for titrating most mineral acids, strong bases, estimating alkalinity of waters; useless for organic acids. In dyeing and printing of textiles.

What are the applications of Application

Methyl orange is a pH indicator dye for titrations

Definition

An acid–base indicator that is red in solutions below a pH of 3 and yellow above a pH of 4.4. As the transition range is clearly on the acid side, methyl orange is suitable for the titration of an acid with a moderately weak base, such as sodium carbonate.

Definition

methyl orange: An organic dyeused as an acid–base indicator. Itchanges from red below pH 3.1 toyellow above pH 4.4 (at 25°C) and isused for titrations involving weakbases.

Preparation

4-Aminobenzenesulfonic acid diazo, and N,N-dimethylaniline coupling.

General Description

Orange powder.

Air & Water Reactions

Azo dyes can be explosive when suspended in air at specific concentrations. Insoluble in water.

Reactivity Profile

Methyl Orange is an azo compound. Azo, diazo, azido compounds can detonate. This applies in particular to organic azides that have been sensitized by the addition of metal salts or strong acids. Toxic gases are formed by mixing materials of this class with acids, aldehydes, amides, carbamates, cyanides, inorganic fluorides, halogenated organics, isocyanates, ketones, metals, nitrides, peroxides, phenols, epoxides, acyl halides, and strong oxidizing or reducing agents. Flammable gases are formed by mixing materials in this group with alkali metals. Explosive combination can occur with strong oxidizing agents, metal salts, peroxides, and sulfides.

Purification Methods

Recrystallise it twice from hot water, then wash it with a little EtOH followed by diethyl ether. It is an indicator: pH 3.1 (red) and pH 4.4 (yellow). [Beilstein 16 IV 510.]

Properties and Applications

orange. The strong sulfuric acid for green light yellow, diluted into red orange. The dye solution to join strong hydrochloric acid for orange red; Add thick sodium hydroxide solution for green light yellow.