Study Notes
Water is essential for life, but it often contains impurities that must be removed to make it safe for consumption. Various tests and treatments are used to ensure water quality.
- Anhydrous Cobalt(II) Chloride — changes color in the presence of water.
Example: Blue anhydrous cobalt(II) chloride turns pink when water is present. - Anhydrous Copper(II) Sulfate — changes color in the presence of water.
Example: White anhydrous copper(II) sulfate turns blue when water is present. - Filtration — process to remove large insoluble substances from water.
Example: Water passes through sand and gravel filters. - Chlorination — process to kill microorganisms in water.
Example: Adding chlorine to water supply to kill bacteria. - Pollutants — substances that contaminate water and air.
Example: Heavy metals, pesticides, and carbon monoxide. - Rusting — chemical reaction of iron with oxygen and water.
Example: Iron rusts when exposed to air and moisture.
Exam Tips
Key Definitions to Remember
- Anhydrous Cobalt(II) Chloride
- Anhydrous Copper(II) Sulfate
- Filtration
- Chlorination
- Pollutants
- Rusting
Common Confusions
- Confusing the color changes of cobalt(II) chloride and copper(II) sulfate.
- Assuming all natural water is safe to drink without treatment.
Typical Exam Questions
- What color does anhydrous cobalt(II) chloride turn in the presence of water? It turns pink.
- How does filtration work in water treatment? It removes large insoluble substances by passing water through filters.
- What is the purpose of chlorination in water treatment? To kill microorganisms in the water.
What Examiners Usually Test
- Understanding of chemical tests for water.
- Knowledge of water treatment processes and their purposes.
- Awareness of common water and air pollutants and their effects.