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Acid Base Concepts
A topic from the subject of Inorganic Chemistry in Chemistry.
Acid-Base Concepts in Chemistry
Key Points:
- Acids donate H+ ions (protons), while bases accept H+ ions.
- pH scale measures acidity or basicity, ranging from 0-14:
- 0-6: Acidic
- 7: Neutral
- 8-14: Basic
- Strong acids and bases completely dissociate in water, while weak acids and bases only partially dissociate.
- Acids and bases undergo neutralization reactions, forming salts and water.
- Conjugate acid-base pairs differ by the exchange of a proton.
Main Concepts:
- Arrhenius Theory: Defines acids as substances that produce H+ ions and bases as substances that produce OH- ions in water.
- Brønsted-Lowry Theory: Defines acids as proton donors and bases as proton acceptors.
- Lewis Theory: Defines acids as electron-pair acceptors and bases as electron-pair donors.
- pH: Negative logarithm of the H+ ion concentration, representing acidity or basicity.
- pKa: Negative logarithm of the acid dissociation constant, indicating the strength of an acid.
- Buffer Solutions: Solutions that resist pH changes by maintaining a constant H+ ion concentration.
Neutralization Reaction: An Acid-Base Experiment
Materials:
- Hydrochloric acid (HCl) solution, 0.1 M
- Sodium hydroxide (NaOH) solution, 0.1 M
- Phenolphthalein indicator
- 10 mL graduated cylinder
- Erlenmeyer flask
- Buret
- Pipette
- Safety goggles and gloves
Procedure:
- Wear appropriate safety gear.
- Fill a buret with the NaOH solution.
- Measure 10 mL of the HCl solution into an Erlenmeyer flask.
- Add 2-3 drops of phenolphthalein indicator to the HCl solution.
- Slowly add the NaOH solution from the buret to the HCl solution, swirling the flask constantly.
- Observe the color change of the indicator.
- Continue adding the NaOH solution until the indicator turns a faint pink color.
- Record the volume of NaOH solution used.
Key Procedures:
- Use precise measurements to ensure accurate results.
- Swirl the flask constantly during the titration to ensure thorough mixing.
- Observe the color change of the indicator carefully to determine the endpoint.
Significance:
This experiment demonstrates the neutralization reaction between an acid (HCl) and a base (NaOH), resulting in the formation of a salt (NaCl) and water. It also introduces the concept of titration, a technique commonly used in chemistry to determine the concentration of unknown solutions.