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Chemistry
General Chemistry
Acids and Bases
Definitions and Properties
Arrhenius Definition
Acids produce H⁺ ions in water
Bases produce OH⁻ ions in water
Example of acids: HCl, H₂SO₄
Example of bases: NaOH, KOH
Brønsted-Lowry Definition
Acids are proton donors
Bases are proton acceptors
Conjugate acid-base pairs
Example of acid-base reaction: NH₃ + H₂O ⇌ NH₄⁺ + OH⁻
Lewis Definition
Acids are electron pair acceptors
Bases are electron pair donors
Includes broader range of substances
Example: BF₃ as a Lewis acid
Properties of Acids
Sour taste
Turn blue litmus paper red
React with metals to produce hydrogen gas
Conduct electricity in solution
Properties of Bases
Bitter taste
Turn red litmus paper blue
Slippery feel
Conduct electricity in solution
pH and pOH
Definition of pH
Scale from 0 to 14
Neutral pH = 7
Acidic pH < 7
Basic pH > 7
Calculating pH
pH = -log[H⁺]
Relationship with pOH: pH + pOH = 14
Definition of pOH
Measure of hydroxide ion concentration
pOH = -log[OH⁻]
Chemical significance of pH
Impact on biological systems
Influence on chemical reactivity
Acid-Base Titration
Purpose and applications
Determining concentration of unknown solution
Neutralization reaction as the basis
Indicators
Phenolphthalein, methyl orange, bromothymol blue
End point vs. equivalence point
Titration curve
Strong acid with strong base
Weak acid with strong base
Strong acid with weak base
Calculating unknown concentrations
Using titration data: \( M_1V_1 = M_2V_2 \)
Buffers
Definition and function
Resist changes in pH upon addition of small amounts of acid or base
Composed of weak acid and its conjugate base or weak base and its conjugate acid
Buffer capacity
The amount of acid or base the buffer can neutralize
Depends on concentrations of the buffer components
Henderson-Hasselbalch Equation
\( pH = pK_a + \log \left(\frac{[A⁻]}{[HA]}\right) \)
Useful for calculating pH of a buffer solution
Biological significance of buffers
Blood buffering systems (e.g., bicarbonate buffer)
Importance in maintaining pH stability in physiological processes
Strengths of Acids and Bases
Strong acids and bases
Strong acids fully dissociate in water (e.g., HCl, HNO₃)
Strong bases fully dissociate in water (e.g., NaOH, KOH)
Weak acids and bases
Weak acids partially dissociate in water (e.g., acetic acid)
Weak bases partially dissociate in water (e.g., ammonia)
Measuring strength
Acid dissociation constant (Kₐ)
Base dissociation constant (K_b)
Relating Kₐ and K_b to acid/base strength
Applications and Importance
Industrial applications
Acids and bases in manufacturing (e.g., sulfuric acid in fertilizers)
Importance in chemical synthesis and processing
Environmental impact
Acid rain and its effects on ecosystems
Role in remediation strategies
Everyday uses
Acids in food and beverages (e.g., citric acid, vinegar)
Bases in cleaning products (e.g., baking soda)
8. Solutions
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10. Electrochemistry