Grade 9
  1. Matter and its nature  1.1. Introduction to matter  1.2. Physical and chemical properties of matter  1.3. States of matter  1.3.1. Solid state  1.3.2. Fluid state  1.3.3. Gaseous state  1.3.4. Plasma and Bose–Einstein condensate  1.4. Changes in the states of matter  1.4.1. Melting and freezing  1.4.2. Evaporation and Condensation  1.4.3. Sublimation and deposition  1.5. Classification of matter  1.6. Elements, Compounds, and Mixtures  1.7. Pure substances and impurities  1.8. Separation Techniques  1.8.1. Filtration  1.8.2. Distillation  1.8.3. Crystallization  1.8.4. Chromatography  1.8.5. Centrifugation  1.8.6. Sublimation  1.8.7. Decantation and sedimentation
  2. Atomic Structure  2.1. Discovery of atoms  2.2. Dalton's atomic theory  2.3. Structure of the atom  2.4. Subatomic particles  2.5. Atomic number and mass number  2.6. Isotopes and Isobars  2.7. Electronic configuration  2.8. Bohr's atomic model  2.9. Modern Atomic Model (Quantum Mechanical Model - Introduction)  2.10. Valency and chemical bonding
  3. C hemical reactions and equations  3.1. Introduction to Chemical Reactions  3.2. Chemical Equation Formulation  3.3. Balancing Chemical Equations  3.4. Types of Chemical Reactions  3.4.1. Combination Reactions  3.4.2. Decomposition reactions  3.4.3. Displacement reactions  3.4.4. Double displacement reactions  3.4.5. Redox reactions  3.4.6. Endothermic and Exothermic Reactions  3.5. Effects of chemical reactions  3.6. Energy Changes in Chemical Reactions  3.7. Catalysts and their role in reactions
  4. Periodic table and periodicity  4.1. History of Periodic Classification  4.2. Mendeleev's periodic table  4.3. Modern Periodic Table  4.4. Periods and groups in the periodic table and periodicity  4.5. Trends in the Periodic Table  4.5.1. Atomic size  4.5.2. Ionization Energy  4.5.3. Electron affinity  4.5.4. Electronegativity  4.5.5. Metallic and Non-Metallic Properties  4.6. Noble gases and their properties
  5. Chemical bond  5.1. Introduction to Chemical Bonding  5.2. Types of chemical bonds  5.2.1. Ionic bond  5.2.2. Covalent bond  5.2.3. Metallic bond  5.2.4. Hydrogen bonding  5.2.5. Van der Waals force  5.3. Properties of Ionic and Covalent Compounds  5.4. Molecular Structure and Geometry (VSEPR Theory - Basics)
  6. Acids, Bases and Salts  6.1. Introduction to Acids and Bases  6.2. Properties of Acids  6.3. Properties of bases  6.4. pH scale and its importance  6.5. Indicators and their uses  6.6. Neutralization reactions  6.7. Strength of Acids and Bases (Strong vs. Weak)  6.8. Preparation of salts  6.9. Uses of acids, bases and salts in daily life
  7. Metals and Nonmetals  7.1. Physical Properties of Metals  7.2. Physical Properties of Nonmetals  7.3. Chemical properties of metals  7.4. Chemical Properties of Nonmetals  7.5. Reactivity Series of Metals  7.6. Extraction of metals  7.7. Corrosion and its prevention  7.8. uses of metals and nonmetals
  8. Carbon and its compounds  8.1. Introduction to Carbon  8.2. Allotropes of carbon (diamond, graphite, fullerene)  8.3. Hydrocarbons  8.3.1. Hydrocarbons  8.3.2. Alkene  8.3.3. Alkynes  8.4. Functional groups in organic chemistry  8.5. Isomerism in organic compounds  8.6. Alcohols and Carboxylic Acids  8.7. Soaps and detergents  8.8. Polymers (Introduction to Natural and Synthetic Polymers)
  9. Solutions and Mixtures  9.1. Types of mixtures  9.2. Homogeneous and Heterogeneous Mixtures  9.3. Concentration of solutions  9.4. Solubility and factors affecting solubility  9.5. Suspensions and Colloids  9.6. Saturated, unsaturated and supersaturated solutions
  10. Air and atmosphere  10.1. Composition of air  10.2. Role of gases in the atmosphere  10.4. Acid rain and its effects  10.5. Greenhouse effect and global warming  10.6. Ozone layer and its depletion  10.7. Air pollution control measures
  11. Water and its importance  11.1. Composition and properties of water  11.2. Hardness of water (temporary and permanent hardness)  11.3. Causes of water pollution  11.4. Effects of Water Pollution  11.5. Water purification methods (filtration, boiling, chlorination)
  12. Industrial Chemistry  12.1. Introduction to Industrial Chemistry  12.2. Important industrial chemicals (sulfuric acid, ammonia, sodium hydroxide)  12.3. Chemical processes in industry  12.4. Uses of Industrial Chemistry in Daily Life  12.5. Environmental impact of industrial chemical processes

Grade 9 ↓


Acids, Bases and Salts


Understanding acids, bases, and salts is an essential part of chemistry, especially at the high school level. These compounds play a vital role in various chemical processes and everyday life applications. Let's learn in detail about the characteristics, reactions, and applications of acids, bases, and salts.

What are acids?

Acids are substances that taste sour and have a pH level less than 7. They are commonly found in foods and have properties that can be used in many chemical processes.

Properties of acids

  • Their taste is sour.
  • They turn blue litmus paper red.
  • They can conduct electricity in a solution.
  • They react with bases to form salt and water.
  • They release hydrogen ions (H+) in aqueous solution.

Here is a visual representation of an acid molecule:

H A

Examples of common acids

  • Hydrochloric acid (HCl) – found in stomach acid
  • Citric acid (C6H8O7) – found in citrus fruits such as lemons and oranges
  • Sulfuric acid (H2SO4) - used in car batteries
  • Acetic acid (CH3COOH) - found in vinegar

What are the bases?

Bases are compounds that, unlike acids, are bitter-tasting and slippery. They play an important role as cleaning agents and in other chemical reactions.

Properties of bases

  • Bitter in taste.
  • They turn red litmus paper blue.
  • They can conduct electricity in a solution.
  • Reacts with acids to form salt and water.
  • Release hydroxide ions (OH -) in aqueous solution.

Here is a representation of a base molecule:

Oh B

Examples of common bases

  • Sodium hydroxide (NaOH) - used in making soap
  • Calcium hydroxide (Ca(OH)2) - used in plaster
  • Ammonium hydroxide (NH4OH) - used as a cleaner
  • Potassium hydroxide (KOH) - used in batteries

Ph scale

The pH scale is a measurement of how acidic or alkaline a solution is, ranging from 0 to 14. It's important to understand where acids and bases fall on this scale.

Representation of pH scale:

0 7 14 Acidic Basic

Acids have a pH value less than 7. Neutral solutions such as pure water have a pH value of 7. Bases have a pH value greater than 7.

Salts

Salts are ionic compounds that are formed when acids react with bases. In these, a positive ion is formed from the base and a negative ion is formed from the acid.

Properties of salts

  • They may be soluble or insoluble in water.
  • Their melting point and boiling point are high.
  • They are usually neutral, that is, their pH value is close to 7.

Examples of normal salts

  • Sodium chloride (NaCl) - common table salt
  • Potassium nitrate (KNO3 ) - used in fertilizers
  • Calcium carbonate (CaCO3) - found in chalk and limestone
  • Magnesium sulfate (MgSO4 ) - used in bath salts

Formation of salts

When an acid reacts with a base, a neutralization reaction occurs, forming salt and water. Here the general reaction is shown as follows:

Acid + Base → Salt + Water

For example, when hydrochloric acid reacts with sodium hydroxide, sodium chloride and water are formed:

HCl + NaOH → NaCl + H2O

Applications and uses

Applications of acids

  • Food industry: Citric acid is used to preserve food and add a sour taste.
  • Cleaning agent: Acetic acid, found in vinegar, is used in cleaning products.
  • Industry: Sulphuric acid is used in the manufacture of fertilizers and in petroleum refining.

Applications of bases

  • Personal care: Bases such as sodium hydroxide are used in soap production.
  • Agriculture: Lime, which is calcium hydroxide, helps neutralize acidic soils.
  • Chemical industry: Ammonia solution is used as a cleaning agent in industries.

Applications of salts

  • Preservation: Sodium chloride is used to preserve foods by preventing the growth of bacteria.
  • Health care: Epsom salts (magnesium sulfate) are used to relieve muscle pain.
  • Construction: Calcium carbonate is an essential building material as it is found in cement and lime.

Conclusion

Acids, bases and salts are fundamental components of chemical reactions in both natural and industrial processes. By understanding their properties and reactions, we can effectively apply this knowledge to everyday applications, from food production to cleaning and industry.

These compounds highlight the complex nature of chemical interactions and their wide applications, and provide essential skills in many areas of study and work.


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Acids, Bases and Salts

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