Grade 7
  1. Introduction to Chemistry  1.1. What is Chemistry?  1.2. Importance of chemistry in daily life  1.3. Branches of chemistry  1.4. Scientific Method in Chemistry  1.5. Laboratory Safety Rules and Precautions  1.6. Common Laboratory Equipment and Their Uses  1.7. Units of measurement in chemistry
  2. Matter and its properties  2.1. Definition of Matter  2.2. Classification of matter  2.3. Properties of matter  2.3.1. Physical properties  2.3.2. Chemical properties  2.4. States of matter  2.4.1. Solid state  2.4.2. Fluid state  2.4.3. Gaseous state  2.4.4. Plasma and Bose–Einstein condensates  2.5. Changes in the states of matter  2.5.1. Melting and freezing  2.5.2. Evaporation and Condensation  2.5.3. Sublimation and deposition  2.6. Density and its applications  2.7. Diffusion and its importance
  3. Elements, Compounds, and Mixtures  3.1. Definition of the element  3.2. Classification of elements  3.3. Metals, Nonmetals and Metalloids  3.4. Noble gases and their properties  3.5. Introduction to the Periodic Table  3.6. Definition of Compound  3.7. Properties of Compounds  3.8. Introduction to Chemical Formulas  3.9. Definition of Mixture  3.10. Types of mixtures  3.10.1. Homogeneous mixture  3.10.2. Heterogeneous mixtures  3.11. Difference Between Compounds and Mixtures  3.12. Solutions, Colloids and Suspensions
  4. Separation of mixtures  4.1. Need for separation of mixtures  4.2. Separation methods  4.2.1. Filtration  4.2.2. Sedimentation and decantation  4.2.3. Evaporation  4.2.4. Crystallization  4.2.5. Distillation  4.2.6. Chromatography  4.2.7. Magnetic Separation  4.2.8. Centrifugation
  5. Atomic Structure  5.1. Introduction to Atoms  5.2. Structure of the atom  5.2.1. Nucleus and electron cloud  5.3. Subatomic particles  5.3.1. Proton  5.3.2. Neutron  5.3.3. Electrons  5.4. Atomic number and mass number  5.5. Isotopes and their uses  5.6. Ions and ion formation
  6. Periodic table  6.1. Introduction to the Periodic Table  6.2. Groups and periods  6.3. Trends in the Periodic Table  6.3.1. Atomic Size  6.3.2. Metallic and non-metallic character  6.3.3. Electronegativity  6.3.4. Reactivity of the elements  6.4. Alkali metals and their properties
  7. Chemical bond  7.1. Why do atoms form bonds?  7.2. Types of chemical bonds  7.2.1. Ionic bond  7.2.2. Covalent bond  7.2.3. Metal Bond  7.3. Properties of Ionic and Covalent Compounds  7.4. Intermolecular forces
  8. Chemical reactions  8.1. Introduction to Chemical Reactions  8.2. Signs of a chemical reaction  8.3. Types of Chemical Reactions  8.3.1. Combination Reactions  8.3.2. Decomposition reactions  8.3.3. Displacement reactions  8.3.4. Double displacement reactions  8.3.5. Combustion reactions  8.4. Law of conservation of mass  8.5. Balancing simple chemical equations
  9. Acids, Bases and Salts  9.1. Definition of Acid and Base  9.2. Properties of Acids  9.3. Properties of bases  9.4. pH Scale and Indicators  9.5. Neutralization reactions  9.6. Common Acids and Bases in Everyday Life  9.7. Preparation and use of salts  9.8. Strong and weak acids and bases
  10. Solutions and Solubility  10.1. Definition of Solution  10.2. Components of the solution  10.2.1. Solvent  10.2.2. solute  10.3. Factors Affecting Solubility  10.4. Concentration of solutions  10.5. Saturated and unsaturated solutions  10.6. Colloids and suspensions  10.7. Solubility curve and its interpretation
  11. Air and atmosphere  11.1. Composition of air  11.2. Properties of gases in the air  11.3. Importance of Oxygen and Carbon Dioxide  11.4. Air pollution and its effects  11.5. Greenhouse effect and global warming  11.6. Ways to reduce air pollution  11.7. Ozone layer and its importance
  12. Water and its importance  12.1. Properties of Water  12.2. Water as the universal solvent  12.3. Importance of water for life  12.4. Water pollution and its effects  12.5. Water Purification  12.5.1. Filtration  12.5.2. boil  12.5.3. Chlorination in water purification  12.5.4. reverse osmosis  12.6. Hard and soft water  12.7. Water cycle and its importance
  13. Fuel and energy  13.1. Types of fuel  13.1.1. Fossil fuels  13.1.2. Renewable energy sources  13.2. Combustion and energy release  13.3. Global warming and its effects  13.4. Alternative sources of energy  13.5. Ways to conserve energy
  14. Metals and Nonmetals  14.1. Physical and chemical properties of metals  14.2. Physical and Chemical Properties of Non-Metals  14.3. Difference Between Metals and Nonmetals  14.4. Uses of metals and nonmetals  14.5. Corrosion of metals and its prevention  14.6. Alloys and their importance
  15. Plastics and polymers  15.1. Natural and synthetic polymers  15.2. Properties of plastics  15.3. Biodegradable and Non-Biodegradable Plastics  15.4. Environmental impact of plastic  15.5. Recycling and waste management in plastics and polymers  15.6. Daily Uses of Polymers
  16. Introduction to Organic Chemistry  16.1. Basic definitions of organic chemistry  16.2. Carbon Compounds in Daily Life  16.3. Hydrocarbons  16.4. Simple functional groups (alcohols and carboxylic acids)  16.5. Importance of organic compounds in industry

Grade 7 → Water and its importance → Water Purification ↓


Filtration


Filtration is one of the most important ways to purify water and make it safe to drink. This process involves separating solid impurities from water using a filter. Filters come in all sizes and are made of different materials, each with the same purpose: removing unwanted substances from water.

What is filtration?

In simple terms, filtration is a process used to separate solids from liquids by passing the mixture through a barrier. This barrier is known as the filter. The filter allows the liquid portion, or filtrate, to pass through while retaining the solid particles, called residues or particulates.

How filtration works

Filtration works like this: The filter is usually made of permeable (or semi-permeable) material such as paper, cloth, or sand. When a mixture of a solid and a liquid (for example, muddy water) is poured over the filter, the liquid component passes through, while the solid particles are trapped. Imagine you are pouring tea through a strainer; the tea leaves are caught by the strainer, and the tea flows into your cup.

Solid Filter Liquid

Materials used in filtration

Filters can be made from a variety of materials, depending on what is being filtered and for what purpose:

  • Paper: Commonly used in laboratories and coffee filters. They are effective for small-scale filtration.
  • Sand: Often used for water purification in water treatment plants. Sand filters can trap large particles and are very efficient.
  • Charcoal: Also known as carbon filters, these are used in home water filters because they can absorb a wide range of impurities.
  • Cloth: Used in everyday situations such as straining juice with cheesecloth. These can be reused after cleaning.

Types of filtration methods

Filtration can be done in several ways, depending on the desired result:

  • Simple filtration: This is the most basic form of filtration where gravity pulls the liquid through the filter.
  • Vacuum filtration: A vacuum pump is used to pull the liquid through the filter more quickly.
  • Pressure filtration: Pressure is applied to a fluid to force it through a filter, common in industrial settings.

Importance of filtration in water purification

Filtration plays an important role in providing clean drinking water. Here are some benefits:

  • Removal of solid impurities: Filtration effectively removes solid impurities such as sand, silt, and clay, leaving the water clear.
  • Improves taste and odor: Filtration helps remove substances that can cause bad taste and odor.
  • Germ reduction: Although filtration is not effective against all germs, it can reduce some bacteria and protozoa when combined with other treatment processes.

Example: If you take muddy water from a river and pass it through a piece of cloth, the water that comes out will contain fewer particles. This is because the cloth acts as a filter.

Obtaining safe drinking water

Filtration is often combined with other purification methods to ensure that water is safe to drink:

  • Distillation: Boiling water to make steam and then re-condensing it to remove impurities.
  • Chlorination: The addition of chlorine to kill bacteria and other microorganisms.
  • UV treatment: Exposing water to ultraviolet light to kill or inactivate microorganisms.

Filtration at home

You can perform simple filtration at home using everyday items. For example, a coffee filter or clean cloth can be used to filter liquids.

  1. Take a bowl and place a wire or plastic strainer over it.
  2. Place a coffee filter or piece of clean cloth over the strainer.
  3. Pour the liquid mixture into it. The filter will trap larger particles and impurities.
Strainer Water

Conclusion

Filtration is an important process in water purification. It removes unwanted particles, improves taste and odor, and plays a vital role in providing clean and safe drinking water. Understanding the process and its importance helps us understand how far tap water travels before it reaches us.

Although filtration is effective, it is often used in conjunction with other treatment methods to ensure comprehensive water purification. Access to clean water is essential to life, health, and well-being, making filtration an important topic in both elementary chemistry and everyday life.


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