Grade 8
  1. Introduction to Chemistry  1.1. Nature and scope of chemistry  1.2. Importance of chemistry in daily life  1.3. Chemistry and its relation with other sciences  1.4. The role of chemistry in industry, medicine and the environment  1.5. Scientific investigation and experimental methods in chemistry
  2. Matter and its properties  2.1. Definition and classification of matter  2.2. Physical and chemical properties of matter  2.3. Law of conservation of matter  2.4. Extensive and Intensive Properties of Matter  2.5. Kinetic molecular theory of matter  2.6. States of matter: solids, liquids, gases, plasmas, and Bose-Einstein condensates  2.7. Changes in state and energy are involved  2.8. Diffusion and Brownian motion
  3. Elements, Compounds, and Mixtures  3.1. Definition and differences between elements, compounds, and mixtures  3.2. Atomic Structure and Atomic Number  3.3. Chemical symbols and formulas  3.4. Trends in the Periodic Table (Groups and Periods)  3.5. Classification of Elements: Metals, Nonmetals and Metalloids  3.6. Rare Earth Elements and Transition Metals  3.7. Types of mixtures: homogeneous and heterogeneous  3.8. Separation of Mixtures Using Physical and Chemical Methods
  4. Separation Techniques  4.1. Filtration, Sedimentation and Decantation  4.2. Evaporation and crystallization  4.3. Distillation and Fractional Distillation  4.4. Chromatography and its applications  4.5. Sublimation in the purification of compounds  4.6. The role of centrifugation in biochemical processes
  5. Atomic Structure  5.1. Dalton's atomic theory  5.2. Structure of the atom: protons, neutrons and electrons  5.3. Bohr's atomic model  5.4. Introduction to Quantum Mechanical Model  5.5. Electron Configuration and Energy Levels  5.6. Excitation and emission spectra  5.7. Isotopes and their applications
  6. Periodic Table and Chemical Trends  6.1. History and Development of the Periodic Table  6.2. Modern periodic law  6.3. Periodicity and trends in atomic and ionic sizes  6.4. Ionization Energy, Electron Affinity and Electronegativity  6.5. Introduction to Lanthanides and Actinides  6.6. Application of periodic trends in chemistry
  7. Chemical Bonding and Molecular Structure  7.1. Types of chemical bonds: ionic, covalent and metallic bonds  7.3. Polar and Nonpolar Molecules  7.4. Hydrogen bonding and its applications  7.5. Intermolecular forces: dipole-dipole, London dispersion force
  8. Chemical Reactions and Stoichiometry  8.1. Chemical Equations and Balance  8.2. Types of Chemical Reactions: Combination, Decomposition, Displacement and Redox  8.3. Introduction to stoichiometry and the mole concept  8.4. Limiting reactant in chemical equations  8.5. Reaction rate, catalyst, and factors affecting reaction rate
  9. Acids, Bases and Salts  9.1. Definition and Properties of Acids and Bases  9.2. Strong vs. Weak Acids and Bases  9.3. pH Scale and pH Calculation  9.4. Neutralization reactions  9.5. Buffer solutions and their importance  9.6. Applications of Acids, Bases and Salts in Daily Life
  10. Solutions and Solubility  10.1. Definition of Solution, Solute, and Solvent  10.2. Factors Affecting Solubility  10.3. Concentration units: molarity and molality  10.4. Saturated, unsaturated and supersaturated solutions  10.5. Concept of osmosis and reverse osmosis  10.6. Concentrative properties of solutions
  11. Gases and Gas Laws  11.1. Properties of gases  11.2. Introduction to Ideal and Real Gases  11.3. Boyle's Law, Charles' Law and Avogadro's Law  11.4. Ideal Gas Equation and Its Applications  11.5. Application of Gas Laws in Real Life
  12. Thermochemistry and energy transformation  12.1. Energy in Chemical Reactions  12.2. Exothermic vs. Endothermic Reactions  12.3. Heat and Enthalpy Changes  12.4. Calorimetry and heat transfer in reactions
  13. Metals and Nonmetals  13.1. Physical and Chemical Properties of Metals and Nonmetals  13.2. Reactivity Series of Metals  13.3. Corrosion and its prevention  13.4. Extraction of metals from ores  13.5. Uses of metals and non-metals in daily life
  14. Introduction to Organic Chemistry  14.1. Characteristics of carbon and organic compounds  14.2. Functional groups and their importance  14.3. Simple Hydrocarbons: Alkenes, Alkenes and Alkynes  14.4. Isomerism in organic compounds  14.5. Introduction to polymers and their uses
  15. Environmental Chemistry and Sustainability  15.1. Green Chemistry Principles  15.2. Effects of Chemical Pollution on Ecosystems  15.3. Acid rain and its effects  15.4. Ozone layer depletion and global warming  15.5. Waste Management and Recycling in Chemistry

Grade 8 ↓


Solutions and Solubility


In chemistry, solutions are an important topic that helps us understand how different substances mix. This knowledge helps us understand how salt dissolves in water or how sugar dissolves in tea. Solutions also help us understand many other concepts in science, and it plays an important role in our daily lives.

What is the solution?

A solution is a special type of homogeneous mixture made up of two or more substances. A solution contains a solute (the substance that dissolves) and a solvent (the substance that is dissolved). The most common example of a solution is salt water, where salt is the solute and water is the solvent.

Types of solutions

Solutions can be found in different states of matter: solid, liquid, and gas. Here are examples of each:

  • Solid solutions (e.g., alloys such as brass, a mixture of copper and zinc)
  • Liquid solutions (e.g., vinegar, a mixture of acetic acid in water)
  • Gaseous solutions (e.g., mixtures of air, oxygen, nitrogen, and other gases)

Understanding solubility

Solubility is the ability of a solute to dissolve in a solvent at a given temperature and pressure. Solubility is an important concept to understand when studying solutions. It is usually expressed as the amount of solute (e.g. grams) that can be dissolved in 100 milliliters (mL) of solvent at a specific temperature.

Factors affecting solubility

There are several factors that affect how well a solute dissolves in a solvent:

  • Temperature: In general, solubility increases as temperature increases. For example, more sugar can dissolve in hot water than in cold water.
  • Pressure: This mainly affects gases. High pressure increases the solubility of gas in liquids. For example, carbonated drinks are bottled at high pressure to dissolve more carbon dioxide gas.
  • Nature of solute and solvent: Similar substances dissolve in each other. For example, polar solutes dissolve in polar solvents, and nonpolar solutes dissolve in nonpolar solvents. This is often summarized by the phrase "like dissolves like."

Visualization of the solution

Let's visualize how a solution is formed. Below is a graphical representation of how salt dissolves in water using simple shapes.

Salt (Solute) Water (solvent) Dissolve

Understanding saturated, unsaturated, and supersaturated solutions

Solutions can be classified based on how much solute is dissolved in the solvent:

  • Unsaturated solution: More solute can still be dissolved in the solvent.
  • Saturated solution: The maximum amount of solute dissolves at a given temperature. Adding more solute will not dissolve more solute.
  • Supersaturated solution: An increase in temperature causes more solute to dissolve than the normal maximum. Cooling this solution may lead to crystallization of the excess solute.

Lesson example of a saturated solution

Consider a glass of water, and you start adding sugar to it. Initially, the sugar dissolves easily. However, as you add more sugar, and eventually you reach a point where no matter how much you stir, the sugar will not dissolve any more. At this point, the solution becomes saturated.

How to calculate solubility

Suppose we have 36 g of salt that can dissolve in 100 mL of water at room temperature. To express this solubility, we can write:

Solubility = (amount of solute / amount of solvent) * 100
          = (36 g / 100 ml) * 100
          = 36%

Examples of solubility in everyday life

Solubility explains many phenomena we observe every day:

  • Preparing tea: When making tea, flavorings dissolve in hot water, which is a practical application of solubility.
  • Medicinal syrups: Medications are often prepared in liquid form for easy swallowing, using solubilization to combine the various components.
  • Fog and clouds: Water vapor in the air showing how gases dissolve into liquids under different atmospheric conditions.

Conclusion

The concepts of solution and solubility are central to understanding chemistry and have many applications in real life. Understanding how solutes and solvents interact to form solutions gives us a better understanding of the natural and manufactured processes around us. These insights form a fundamental understanding that allows for exploration and innovations in a variety of scientific fields.


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Definition of Solution, Solute, and Solvent

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Solutions and Solubility

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