Ch-10 Acid, Bases and Salts

Ch-10: Acid, Bases and Salts

Class 10th - Chemistry Definitions

Concepts of Acids and Bases:

• Acids and bases are fundamental concepts in chemistry that describe substances with specific properties and behaviors. 
• Acids are characterized by their ability to donate protons, while bases accept protons. 
• They have distinct chemical structures and react with one another to produce salt and water. 
• Acids usually have a sour taste, while bases have a bitter taste. 
• Acids turn blue litmus paper red, while bases turn red litmus paper blue. 

Arrhenius acids and bases:

• An Arrhenius acid is a substance that releases hydrogen ions (H+) into water when dissolved, while an Arrhenius base releases hydroxide ions (OH-).
• Examples of Arrhenius acids include hydrochloric acid (HCl) and acetic acid (CH3COOH), while examples of Arrhenius bases include sodium hydroxide (NaOH) and ammonia (NH3).
• Arrhenius acids and bases are defined based on their behavior in water, and this theory provides a useful foundation for understanding other acid-base theories.

Browsted-Lowry theory:

• The Browsted-Lowry theory of acids and bases focuses on the transfer of protons (H+) between species.
• According to this theory, an acid is a species that donates a proton, while a base is a species that accepts a proton.
• The Browsted-Lowry theory is more general than the Arrhenius theory, as it encompasses reactions that do not involve water.

Equation for self-ionization of water:

• The equation for the self-ionization of water is: 2H2O ⇌ H3O+ + OH-
• This equation describes the process by which water molecules can donate or accept protons, resulting in the formation of hydronium ions (H3O+) and hydroxide ions (OH-).
• The self-ionization of water is an important concept in understanding the pH scale and acid-base chemistry.

Neutralization reaction:

• A neutralization reaction refers to the reaction between an acid and a base, resulting in the formation of a salt and water.
• In this reaction, the hydrogen ions (H+) from the acid combine with the hydroxide ions (OH-) from the base to form water (H2O).
• Examples of neutralization reactions include the reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH) to form sodium chloride (NaCl) and water.

Uses of litmus paper and pH paper/indicators:

• Litmus paper is a type of pH indicator that can be used to determine the acidity or alkalinity of a solution.
• Red litmus paper turns blue in basic solutions and remains red in acidic solutions, while blue litmus paper turns red in acidic solutions and remains blue in basic solutions.
• pH paper, on the other hand, provides a more quantitative measurement of pH, indicating the specific pH value of a solution.
• pH indicators, including both litmus paper and pH paper, are widely used in laboratories, schools, and industries to determine the pH of substances.

Arrhenius Concept of Acids and Bases:

The Arrhenius concept of acids and bases, proposed by Svante Arrhenius, defines an acid as a substance that increases the concentration of hydrogen ions (H+) in solution, while a base increases the concentration of hydroxide ions (OH-) in solution. This concept provides a foundation for understanding acid-base reactions and their behavior. 

Lewis Concept of Acids and Bases:

The Lewis concept of acids and bases, introduced by Gilbert N. Lewis, expands the definition to include substances that accept or donate electron pairs. According to this concept, an acid is an electron pair acceptor, while a base is an electron pair donor. This concept allows for a broader understanding of acid-base reactions, and it is widely used in organic and inorganic chemistry. 

Self-ionization of Water - pH Scale:

Self-ionization of water refers to the process where water molecules spontaneously dissociate into hydrogen ions (H+) and hydroxide ions (OH-). This reaction is responsible for the pH scale, which measures the acidity or alkalinity of a substance. The pH scale ranges from 0 to 14, with 7 being neutral, values below 7 indicating acidity, and values above 7 indicating alkalinity. 

Uses of Salts:

Salts have numerous practical applications in various industries and daily life. They are used as preservatives in food, cosmetics, and pharmaceuticals, as well as in the production of fertilizers, dyes, and cleaning agents. Salts also play a vital role in the functioning of the human body, as electrolytes that maintain proper cell and organ function. 

10th Class Notes | Chemistry 
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