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 ↓


Introduction to Acids and Bases


Welcome to the fascinating world of acids and bases! These substances are all around us. They are present in the food we eat, the drinks we drink, the cleaning products we use, and even in our bodies. It is important to understand acids and bases because they play a vital role in chemistry and have practical applications in many areas of life.

What are acids?

Acids are substances that can donate protons (H +) to another substance. They taste sour, like the taste of lemon juice or vinegar. Acids turn blue litmus paper red and have a pH value less than 7.

Here's a simple acid, hydrochloric acid, often found in stomach acid:

HCl
H Chlorine

In this structure, hydrogen (H) is bonded to chlorine (Cl), forming hydrochloric acid.

Common examples of acids

  • Lemon juice (C 6 H 8 O 7) - citric acid
  • Vinegar (CH 3 COOH) - acetic acid
  • Battery acid (H 2 SO 4) - sulfuric acid

What are the bases?

Bases are substances that can accept protons or donate electron pairs. They taste bitter and feel slippery like soap when touched. Bases turn red litmus paper blue and have a pH greater than 7.

Here's an example of an alkali called sodium hydroxide, which is commonly used in soap making:

NaOH
Na OH

In this structure, sodium (Na) bonds with the hydroxide ion (OH) to form sodium hydroxide.

Common examples of bases

  • Baking soda (NaHCO 3) - sodium bicarbonate
  • Ammonia (NH 3)
  • Milk of magnesia (Mg(OH) 2) - magnesium hydroxide

Understanding pH

The pH scale measures how acidic or alkaline a solution is. It ranges from 0 to 14. A pH of 7 is neutral, indicating a balance between acids and bases. This is the pH of pure water.

When the pH value is less than 7 it indicates an acidic solution, whereas when the pH value is more than 7 it indicates an alkaline solution.

0 7 14

Examples include:

  • pH 3 (acidic): orange juice
  • pH 7 (neutral): pure water
  • pH 10 (basic): milk of magnesia

Neutralization reactions

When acids and bases react with each other, they undergo a neutralization reaction. This reaction usually results in the formation of water and salt.

The general equation for the neutralization reaction is:

Acid + Base → Salt + Water

The reaction between hydrochloric acid and sodium hydroxide is a common example:

HCl + NaOH → NaCl + H 2 O

In this reaction, sodium chloride (NaCl), which is a table salt, is formed along with water.

Applications of Acids and Bases

Acids and bases have many applications in everyday life and industry. Here are some examples:

Domestic use

  • Vinegar: Used in cooking and cleaning. Its acidic nature helps remove stains and odors.
  • Baking soda: Used as a leavening agent in baking. It reacts with acidic ingredients to form carbon dioxide gas which makes baked goods rise.

Industrial uses

  • Sulphuric acid: Used in the manufacture of fertilisers, detergents, and car batteries.
  • Ammonia: Used in cleaning products and as a refrigerant.

Biological uses

  • Hydrochloric acid in the stomach: This acid aids digestion and helps kill bacteria.
  • Bicarbonate ions: These ions present in the blood help maintain the pH balance of the body.

Conclusion

Acids and bases are fundamental concepts in chemistry that affect many aspects of the natural and industrial world. Understanding their properties, behaviors, and reactions helps us better understand the chemical processes that occur around us every day. From the food we eat to the products we use, acids and bases play an integral role in our lives.


Grade 9 → 6.1


U
username
0%
completed in Grade 9

← Prev (6)
Acids, Bases and Salts
Next (6.2) →
Properties of Acids

Comments 



Introduction to Acids and Bases

https://www.chemistryelite.com/g9/6.1?ceal=en