Water: Chemical Tests
Section: 10. Chemistry of the Environment | Syllabus: Cambridge AS Level Physics 9702
Water: Chemical Tests Chemical Tests for Water Water can be detected using specific chemical tests that show characteristic color changes. Anhydrous cobalt(II) chloride: Turns from blue to pink in the presence of water Anhydrous copper(II) sulfate: Turns from white to blue in the presence of water Pure Water Water that contains only H₂O molecules with no dissolved substances.
It has a fixed melting point of 0°C and boiling point of 100°C at standard atmospheric pressure. Testing Purity The purity of water can be tested by measuring its melting point and boiling point: Pure water melts at exactly 0°C Pure water boils at exactly 100°C (at standard atmospheric pressure) Impurities lower the melting point and raise the boiling point Distilled Water Distilled water is water that has been purified by distillation.
It is used in practical chemistry because: It contains no dissolved ions that could interfere with chemical reactions It prevents contamination of experiments It ensures consistent and reliable results
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