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 ↓


boil


Boiling is a common method used to purify water. The process of boiling involves heating water until it reaches its boiling point, which is the temperature at which it changes from a liquid to a gas. For most environments, water boils at 100 degrees Celsius or 212 degrees Fahrenheit. Boiling is an effective technique for killing bacteria, viruses, and parasites present in water, making it safe for drinking and cooking.

The science behind boiling is quite interesting. When water is heated, the molecules begin to move faster, eventually moving so fast that they separate from the surface of the liquid and become steam. This steam is water in the gaseous state. The change from liquid to gas is an important aspect of the boiling process that works to purify water.

H2O

Boiling process

Boiling involves heating water to its boiling point using a heat source. This heat can come from a variety of sources, including a stove, campfire, or electric kettle. As the water reaches the boiling point, it turns into steam, which rises to the surface. During boiling, harmful bacteria and pathogens are neutralized, making the water safe to drink.

To ensure effective purification, it is recommended to boil the water vigorously for at least 1 to 3 minutes. This time allows enough heat to be added to the water to kill most waterborne germs. If you are at a higher altitude where atmospheric pressure is lower, water will boil at a lower temperature. Therefore, longer boiling times may be required at higher altitudes.

Importance of boiling in water purification

Boiling water is one of the simplest and most reliable methods of water purification. It is accessible and does not require any special equipment or chemicals, making it a suitable option in emergency situations or areas without access to advanced purification systems.

An example of the process of boiling can be described as follows:

Step 1: Fill a vessel with water.
Step 2: Place the pot on the heat source.
Step 3: Heat the water until it starts to boil.
Step 4: Maintain a simmer for at least 1 to 3 minutes.
Step 5: Allow the water to cool before drinking it.

Chemical changes during boiling

During boiling, water undergoes a physical change from liquid to gas. This phase change occurs without changing the chemical composition of the water, because the molecular formula remains the same: H 2 O This is an important aspect of the process, because it means the water remains pure.

Visualization of the boiling process

heat source H2O

Benefits and limitations of boiling

One of the primary advantages of boiling is its simplicity and effectiveness. Boiling can eliminate most pathogens responsible for diseases. However, it has some limitations, such as not removing chemical contaminants or toxins present in contaminated water. Additionally, boiling requires a fuel source, which may not always be available or sustainable.

Closing thoughts

In conclusion, boiling is a valuable tool in water purification, providing a simple and effective way to enhance water safety. Although it is not a universal solution to all water contamination issues, it is a practical and easily implementable way to ensure that water is safe to drink. Understanding the boiling process and its limitations invites further exploration into complementary purification technologies.


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