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Created: "2023-08-02T02:45:00.0000000"
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1. Normality: the number of gram equivalents of solute per liter of solution.
2. Titration: a laboratory technique used to determine the concentration of a substance in a solution by reacting it with a known volume and concentration of another substance (titrant) until the reaction reaches an endpoint.
3. Indicator: a substance that changes color at a specific pH, and is used to indicate the equivalence point in a titration.
4. Equiv. weight: the mass of a substance that will react with one mole of hydrogen ions (H+) or hydroxide ions (OH-).
5. pH scale: a scale used to measure the acidity or basicity of a solution. Where: 7 -\> neutral, \< 7 -\> acidic, \> 7 -\> basic.
6. Different kinds of Indicator for different pH:
    1.  Phenolphthalein: Transitions from colorless to pink in the pH range of 8.2-10.0.
    2.  Methyl orange: Changes from red to yellow in the pH range of 3.1-4.4.
    3.  Bromothymol blue: Shifts from yellow to blue in the pH range of 6.0-7.6.
    4.  Litmus: Turns red in acidic solutions and blue in alkaline solutions.
7. Mechanism of Phenolphthalein: Phenolphthalein is a weak acid that exists in two forms: a protonated form (HIn+) and a deprotonated form (In2-). The protonated form is colorless, while the deprotonated form is pink. In acidic solutions, the protonated form predominates, so the solution is colorless. In basic solutions, the deprotonated form predominates, so the solution is pink.
8. Primary Standard Substance: A highly pure and stable substance with a precisely known concentration, used as a reference in titrations and other analytical methods.
9.  Secondary Standard Substance: A substance with a known concentration that is standardized against a primary standard, used when a primary standard is not available or practical.
10. Characteristics of Primary Standard & Secondary Standard Substance.

| Characteristic    | Primary Standard | Secondary Standard                   |
| ----------------- | ---------------- | ------------------------------------ |
| Purity            | Very high        | Not as high as primary standard      |
| Stability         | Very stable      | Less stable than primary standard    |
| Equivalent weight | High             | Lower than primary standard          |
| Cost              | More expensive   | Less expensive than primary standard |