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Acids & Bases

Acids & Bases . NC Essential Standards. 3.2.1 Classify substances using the hydronium and hydroxide concentrations Distinguish between acids and bases based on formula and chemical properties Differentiate between concentration (molarity) and strength (degree of dissociation)

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Acids & Bases

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  1. Acids & Bases

  2. NC Essential Standards • 3.2.1 Classify substances using the hydronium and hydroxide concentrations • Distinguish between acids and bases based on formula and chemical properties • Differentiate between concentration (molarity) and strength (degree of dissociation) • Use pH to identify acids and bases. • Interpret pH scale in terms of the exponential nature of pH values in terms of concentrations. • Relate the color of indicator to pH using ranges provided in a table. • Compute pH, pOH, [H⁺] and [OH⁻] • 3.2.2 Distinguish properties of acids and bases related to taste, touch, reaction with metals, electrical conductivity, and identification with indicators such as litmus paper and phenolphthalein.

  3. Acids & Bases – important aqueous solutions • Properties of acids and bases • https://ed.ted.com/lessons/the-strengths-and-weaknesses-of-acids-and-bases-george-zaidan-and-charles-morton Notes: Make 4 columns to easily jot down notes from the video • Acid properties Base properties Strong Weak

  4. Acid & Base demonstrations • http://www.youtube.com/watch?v=ti_E2ZKZpC4

  5. Arrenhius Definition of Acids and Bases • Acids release H⁺ ion • Also known as hydronium ions (H₃O⁺) • Bases release OH⁻¹ ions • Other definitions: • Bronsted Lowery • Lewis

  6. pH scale

  7. pH scale • pH values • pH = - log [H⁺]

  8. pH Scale Neutral ⇓

  9. Ions in Solutions Neutral [H⁺] [OH⁻] In water: [H⁺]= [ OH⁻] pH = 7 pOH = 7

  10. pOH Scale Neutral ⇓ pH + pOH = 14

  11. Examples of Acids and Bases

  12. pH Scale • http://www.johnkyrk.com/pH.html

  13. pH indicators • What is the approximate pH of the solution tested in the picture? Is the solution an acid or a base? Is it strong or weak?

  14. pH Indicators Litmus Paper Phenolphthalein Blue - indicates base Red - indicates acid

  15. pH Indicators

  16. Universal Indicator Bromothymol Blue Acid = yellow Neutral = green Base = blue

  17. Concentration⇎ Strength • Concentrated or dilute - Molarity • 6M vs. 0.6 M Strength or weak = degree to which acids or bases separate into ions

  18. Strength vs. Concentration • Strength in acids • Based on degree H⁺ ions separate from the anion • Proportion of acid molecules in which H⁺ separate compared to how many acid molecules do not separate • Strong acids = most H⁺ separate • Examples: HCl, HNO₃ and H₂SO₄ • Weak acids = only some H⁺ separate • Examples: HF, HC₂H₃O₂ • Strength of Bases • Strong = most OH⁻ separate from the metal

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