Sodium bisulfate

• Primary sodium sulfate
• Sodium acid sulfate
• Sodium bisulfate

• 7681-38-1
• 10034-88-5 (monohydrate)

White crystalline solid

Fixed

2.12 g · cm -3 ( 20 ° C)

Decomposition from 315 ° C

1080 g · l-1 (at 20 ° C)

Risk

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Sodium hydrogen sulfate ( NaHSO 4 ) is an acidic sodium salt of sulfuric acid. As an anion, it contains the hydrogen sulfate ion. It is also referred to as a primary or sodium acid sulfate; an older name is sodium bisulfate.

The white crystalline solid readily dissolves to form an acidic solution in water:

On further heating, the sodium disulfate decomposes into sodium sulfate and sulfur trioxide:

Production

• The synthesis of sodium bisulfate succeeds moderately warm by the action of concentrated sulfuric acid to sodium chloride. As a byproduct of the gas, hydrogen chloride:

• Concentrated sulfuric acid to sodium hydroxide dropwise until an excess of sulfuric acid is formed. The heat from escaping the water. It remains the desired monohydrate, provided it is not too hot.

• Concentrated sulfuric acid to sodium carbonate or sodium bicarbonate dropwise until no more gas evolved. The resulting water must be removed in a desiccator. Evaporation of the solution is obtained in most cases with sodium disulfate. This can be moistened with water and then dried in a desiccator.

Applications

In food technology, it is used as a firming agent, acidity regulator and carrier. Sodium hydrogen sulfate and sodium sulfate are in the EU as a food additive under the E number 514 with no maximum limit ( quantum satis ) generally approved for food.

Left: sample of sodium hydrogen sulfate. The material is highly hygroscopic, so that, as seen on the image, to form lumps comes that are difficult to crush again.