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 → Elements, Compounds, and Mixtures → Types of mixtures → Definition of the element ↓


Homogeneous mixture


Chemistry is an exciting study of matter and its properties. It helps us understand what everything around us is made of. Part of this study is looking at mixtures, which occur when two or more substances are combined. In this lesson, we will explore a type of mixture known as a "homogeneous mixture."

What are homogeneous mixtures?

A homogeneous mixture is a mixture that has a uniform composition. This means it is the same throughout. If you take a sample from any part of the mixture, the proportion of components in it will be the same as any other sample of that mixture.

Main characteristics of homogeneous mixtures:

  • Uniform structure
  • The components are evenly distributed
  • Cannot see different objects
  • Samples taken from any part of the mixture are identical

Examples of homogeneous mixtures

Let us look at some everyday examples to understand homogeneous mixtures better.

Example 1: Salt water

When salt is dissolved in water, it forms a homogeneous mixture called a solution. The salt (the solute) is evenly distributed throughout the water (the solvent). No matter how much you stir it or how long you let it sit, you can't separate the salt from the water because they are mixed evenly.

NaCl (s) + H 2 O (l) → Na + (aq) + Cl - (aq)
Water Salt

Example 2: Air

Air is another common homogeneous mixture. It is composed primarily of nitrogen and oxygen, as well as small amounts of other gases such as carbon dioxide and argon. These gases are so thoroughly mixed that you can't see or separate them by normal means.

N 2 + O 2 + CO 2 + Ar = Air
Air

Example 3: Vinegar

Vinegar is a homogeneous mixture of acetic acid and water. When you look at vinegar, it appears clear and uniform. You cannot distinguish between acetic acid and water with your eyes, making it a homogeneous mixture.

CH 3 COOH (l) + H 2 O (l) → Vinegar

Visualization of homogeneous mixtures

Homogeneous mixture

The diagram above shows a simplified version of a homogeneous mixture. The different coloured circles represent particles of different substances. Notice how evenly distributed they are. This even distribution is the key to understanding homogeneous mixtures.

Properties and uses of homogeneous mixtures

Homogeneous mixtures have unique properties and practical applications. Here are some of them:

  • Easy separation: Some homogenous mixtures can be separated by simple filtration or evaporation processes, such as separating salt from salt water.
  • Consistent texture: The uniformity of homogeneous mixtures ensures that products such as mayonnaise have a consistent texture.
  • Wide uses: They are found in a variety of industries such as food, pharmaceuticals, and the manufacturing of products such as glass and metals.

Application examples: Alloys

Alloys are another classic example of homogeneous mixtures. They are mixtures of two or more metals. Consider brass, which is an alloy of copper and zinc. The copper and zinc metals are mixed uniformly at the atomic level, resulting in a material with unique properties used for decorative and practical purposes.

Brass = Cu + Zn

How are homogenous mixtures formed?

Creating a homogeneous mixture usually involves physical processes. These include stirring the mixture, heating it, or sometimes using pressure to ensure an even distribution.

Stirring

For example, when making sugar water, you must stir sugar (the solute) into water (the solvent) until the sugar is completely dissolved.

Heating

In some cases, such as in glass making, it is necessary to heat components such as silica, soda, and lime until they melt and form a uniform mixture.

Comparison of homogeneous and heterogeneous mixtures

Now that we have a clear understanding of homogeneous mixtures, let's briefly compare them with heterogeneous mixtures:

Heterogeneous mixtures

  • The components are not evenly distributed
  • Different parts of a mixture have different compositions
  • Examples include salads, trail mix, and granites.
Heterogeneous mixtures

Note that in the example above, the components in a heterogeneous mixture are not evenly distributed. This is an important difference from homogeneous mixtures.

Conclusion

Understanding homogeneous mixtures is fundamental in chemistry. These mixtures are homogeneous, with particles that are evenly distributed. They can be found everywhere in our daily lives, from the air we breathe to the beverages we drink. By recognizing the properties and uses of homogeneous mixtures, we appreciate the complex balance and structure in the substances around us.


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Homogeneous mixture

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