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Read Sea water is a 4.5 percent salt solution.
Sea water does not only contain the salt sodium chloride: Apart from 10.6 g sodium and 18.9 g chloride ions one litre of salt water also contains 1.3 g magnesium and 2.6 g sulfate ions.
Left: 0.2 g samples of salt from the Red Sea (MR), kitchen salt without additives (SO) and kitchen salt with calcium carbonate as an additive for separation (SM) are transferred into three 5-ml injection vials (Liquemin Roche).
For a control experiment an empty vial is used (K).
Middle: After adding of 5 ml battery water and shaking Red Sea salt and salt without additives are completely dissolved while the mixture with kitchen salt + additives is turbid.
Right: 1 teaspoon (4 g) of kitchen salt with additives leaves a sediment of 0.2 ml white solid.
By adding drops of hydrochloric acid to the sediment a gas evolution which is characteristic for carbonates can be seen.