Acids, Bases, and Salts
Explore the properties of acids and bases, understand the pH scale, and learn about neutralization reactions that form salts.
Key Topics & Instructions
▼- Acid-Base Properties: Understand characteristics of acids and bases.
- pH Scale: Learn about pH values and indicators.
- Neutralization: Explore acid-base reactions and salt formation.
- Salt Types: Study different types of salts and their uses.
- pH Scale: Adjust substances to see their pH values and properties.
- Neutralization: Select acid-base pairs to observe salt formation.
- Indicator Colors: Observe color changes with different indicators.
- Review the explanations for understanding acid-base chemistry.
Experiment 1: pH Scale and Indicators
Select different substances to explore their pH values, properties, and indicator color changes.
Experiment 2: Neutralization Reactions
Select different acid-base pairs to understand neutralization reactions and salt formation.
Acids are substances that release H⁺ ions in aqueous solution, taste sour, turn blue litmus red, and have pH values less than 7. Bases are substances that release OH⁻ ions, taste bitter, feel slippery, turn red litmus blue, and have pH values greater than 7. The pH scale measures acidity or basicity from 0 (strong acid) to 14 (strong base), with 7 being neutral. Indicators are substances that change color depending on pH, helping identify acidic or basic nature.
Neutralization Reactions and Salt Formation
Neutralization is a chemical reaction between an acid and a base that results in the formation of salt and water. The general equation is: Acid + Base → Salt + Water. For example: HCl + NaOH → NaCl + H₂O. This reaction involves the combination of H⁺ ions from the acid and OH⁻ ions from the base to form water, while the remaining ions form the salt.
Salts can be classified as: Normal salts (formed by complete neutralization, e.g., NaCl), Acid salts (contain replaceable hydrogen, e.g., NaHCO₃), and Basic salts (contain hydroxide ions, e.g., Zn(OH)Cl). The nature of the salt depends on the strength of the parent acid and base used in neutralization.
The pH of a salt solution depends on the strengths of the parent acid and base: Strong acid + Strong base → Neutral salt (pH = 7), Strong acid + Weak base → Acidic salt (pH < 7), Weak acid + Strong base → Basic salt (pH > 7). This is due to hydrolysis of salt ions in water.
Different indicators show color changes at specific pH ranges: Litmus (Red in acid, Blue in base), Phenolphthalein (Colorless in acid, Pink in base), Methyl Orange (Red in acid, Yellow in base), Universal Indicator (Shows full spectrum of colors across pH range).
Acid-base chemistry has numerous applications: Antacids (neutralize excess stomach acid), Soil treatmentBee stings (treated with baking soda, a base), Wasp stings (treated with vinegar, an acid), Food preservation (using acidic conditions), and Battery acid (sulfuric acid in car batteries).
It's important to distinguish between strength (degree of ionization) and concentration (amount of acid/base per unit volume). A strong acid completely ionizes in water (e.g., HCl), while a weak acid partially ionizes (e.g., CH₃COOH). Concentration is measured in moles per liter, while strength determines the pH value at a given concentration.
