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 → Separation of mixtures → Separation methods ↓


Filtration


Introduction to filtration

Filtration is an essential method of separation used in chemistry to separate solid particles from liquids or gases. It involves a process by which small particles, such as impurities or sediment, are trapped on a filter, allowing the liquid or gas to pass through. This technique is commonly used in laboratories, industrial processes, and even in our daily lives. Understanding the basic principles of filtration helps to understand how different mixtures can be separated into their pure components using simple methods.

Basic concept of filtration

The basic concept of filtration involves the use of a filter medium. This is typically a porous substance that allows small molecules such as water or air to pass through while blocking larger particles. The filter acts as a barrier, retaining solid particles and allowing the liquid or gas to pass through.

Liquid or gas -> filter -> clean liquid or gas + retained solid

Understanding the process with examples

Imagine a scenario where you add sand to water. Over time, the sand will settle to the bottom due to gravity. However, if you use a piece of cloth or a fine mesh as a filter, you can separate the sand from the water more efficiently. This simple act represents filtration.

water + sand clean water

Applications of filtration

Filtration is a versatile process that is used in many areas, such as:

  • Water purification: Filtration systems are used to purify drinking water by removing impurities and pollutants.
  • Air purification: Air filters trap dust, pollen, and other particles, improving indoor air quality.
  • Chemical laboratories: Filtration is used to separate precipitates from liquid solutions.
  • Cooking: Strainers and sieves act as filters to separate solid food particles during cooking.

Types of filtration

Several filtration techniques are used, depending on the nature of the mixture and the size of the particles to be separated:

1. Gravity filtration

Gravity filtration relies on the force of gravity to pull the liquid through a filter paper or medium. It is typically used to separate large particles, such as separating sand from water.

2. Vacuum filtration

Vacuum filtration uses suction to draw the liquid rapidly through the filter. It is more efficient than gravity filtration for smaller particles.

Mixing in funnel -> vacuum system -> filtered solution + solids on filter

3. Pressure filtration

Like vacuum filtration, pressure filtration uses increased pressure to force the liquid through a filter. This is useful in large industrial setups.

The suitability of each method depends on the specific requirements of the process, such as the desired speed of filtration and the nature of the materials involved.

Factors affecting filtration

Several factors can affect the efficiency of the filtration process. These include:

1. Particle size

Smaller particles require filters with finer pores, which can slow down the filtration process.

2. Viscosity of the liquid

More viscous fluids, such as oil, flow through filters slowly than less viscous fluids, such as water.

3. Temperature

Higher temperatures can reduce the viscosity of a liquid, allowing it to pass through the filter more quickly.

Viscosity ∝ 1/temperature

4. Filter material

The material the filter is made of can also affect filtration. For example, a mesh made of metal may allow for faster filtration than a cloth mesh.

Stages of filtration

Following are the steps involved in the basic filtration process:

  1. Preparation: Select the appropriate filter depending on the mixture to be separated.
  2. Installation: Place the filter in the funnel or holder over the container.
  3. Pour the mixture: Carefully pour the mixture into the filter, allowing the liquid to drain out.
  4. Collection: Collect the clear liquid and trapped solids separately.
  5. Cleaning: If possible, clean and dry the filter for reuse.

Advantages and limitations of filtration

Benefits

  • It is simple to execute with minimal tools.
  • Effective for many types of mixtures involving solid-liquid or solid-gas separation.
  • Cost effective for large scale separations.

Boundaries

  • Not suitable for separating very small particles that pass through the filter.
  • Filtration rates can be slow depending on the mix and setup.
  • Some filtrates may require additional methods to achieve complete purification.

Real life examples: Filtration in everyday life

Filtration is part of many everyday processes. For example, when you make coffee, you pour hot water through coffee grounds held in a filter. The filter allows only the coffee-flavored water to pass through, while the coffee grounds remain on the filter.

Coffee Brewer

Other examples include air purifiers, which filter harmful dust particles and allergens from the air, and swimming pool filters, which keep the water clean and free of debris.

Conclusion

Filtration is a fundamental separation technique that plays a vital role in science and everyday life. Understanding its principles, applications, and limitations makes it possible to use it effectively in a variety of fields, ensuring that impurities are removed and desired substances are separated efficiently.


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Filtration

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