Is sodium sulfate acid or base

Experiment of the month
January 2003


5 year experiment of the month
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... then they color indicators. With this projection experiment it can be shown which salts react acidic or basic in aqueous solution.

Explanation:
If a weak acid is neutralized with a lye, a basic salt is formed; the acid anion can take up protons. Acetic acid and carbonic acid are weak acids, so acetates and carbonates have a basic reaction. Phosphoric acid can donate three protons, with the second and third dissociation step corresponding to weak acids. Hydrogen phosphates and phosphates also have an alkaline reaction.
Sulfuric acid is a biprotonic acid. Hydrogen sulfate is also still a strong acid. Ammonium chloride is a salt of the weak base ammonia. Ammonium salts are weakly acidic.
Sodium sulfate, on the other hand, is a salt of a strong acid (sulfuric acid) and a strong base (NaOH). The salt reacts neutrally.

HSO4 + H2O ® SO42– + H3O+
NH4+ + H2O ® NH3 + H3O+
CH3COO + H2O ® CH3COOH + OH
CO32– + H2O® HCO3 + OH
PO43– + H2O ® HPO42– + OH

Acid-base indicators are themselves weak acids or bases (see Experiment 11/2000). Universal indicator is a mixture of several indicators. This allows pH values ​​in the range 1-13 to be displayed through continuous color changes.

Note:
As a practical experiment, the salts can also be placed on moist universal indicator paper on a watch glass

Hazards:
The salts investigated irritate the skin and eyes.

Disposal:
The solutions can be added to the wastewater.

Literature & Links:
Chemistry internship for physicians: Experiment 4.1
own documents

Mrs Dipl.-Chem. Gisela Martinek I thank you very much for your support.


December 2002: Calcium oxalate

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