How to Test for Sulfuric Acid

Sulfuric acid, or H2SO4, is one of the strongest mineral acids -- but only if it is free of impurities. Sulfuric acid can be tested for various impurities, including sulphates of soda, potash, and even lead. Only proper testing can differentiate a pure portion of H2SO4 from its impure counterparts.

Things You'll Need

• A small portion of sulfuric acid
• A platinum sheet
• A heater
• Water
• Concentrated muriatic acid
• Granulated zinc
• A lighter
• A porcelain plate

Instructions

1. 

   Add muriatic acid to a diluted sulfuric acid solution to test for lead.

   Hold a strip of platinum over a burner to heat it. Add H2SO4 to it and allow it to evaporate. Do not remove from the heater till the acid has completely evaporated. If you see a residue, the H2SO4 is not pure.

2. Dilute a sample of H2SO4 in water. Add some drops of muriatic acid in a concentrated form. If the clear solution turns milky white, the H2SO4 contains lead.

3. Mix a portion of H2SO4 with water and granulated zinc, causing hydrogen gas to fume out. Light the gas and hold a cold porcelain plate over it. If you see a deposit of metallic arsenic on the plate, there is arsenic in the acid. Arsenic is one of the most common impurities found in sulfuric acid.

Tips & Warnings

• Testing sulfuric acid is not difficult and needs not be carried out in a chemist's lab. You can conduct the experiments at home, using H2SO4 purchased from your local hardware store.

• Sulfuric acid is a strong acid and can be dangerous if not handled properly. Be very steady and do not rush the experiment.

• If the acid touches your skin, rinse it off immediately with lukewarm water and cover it with a dry, sterile bandage.

• Use extreme caution while placing the platinum strip on the heater.

References

• Chest of books: How To Test Sulphuric Acid
• Chemical land21: SULFURIC ACID (H2SO4)