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ACIDS AND BASES

ACIDS AND BASES. Outline the historical development of acid base theories. Include: Arrhenius , Bronsted -Lowry , Lewis Write balanced acid/base chemical equations. Include: conjugate pairs , amphoteric. Additional KEY Terms Hydroxide Hydronium. ACIDS. Taste sour

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ACIDS AND BASES

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  1. ACIDSAND BASES

  2. Outline the historical development of acid base theories. • Include: Arrhenius, Bronsted-Lowry, Lewis • Write balanced acid/base chemical equations. • Include: conjugatepairs, amphoteric Additional KEY Terms Hydroxide Hydronium

  3. ACIDS • Taste sour • Burn when touching skin • Turn blue litmus red • Neutralize basic solutions • Corrosive to metals • Strong or weak electrolytes You should already be aware of most of these properties…except the taste. Don’t eat stuff in the lab, please. BASES • Taste bitter • Feel slippery • Turn red litmus blue • Neutralize acidic solutions • Strong or weak electrolytes

  4. 1. Arrhenius Definition • Acids • Yield hydrogen ions (H+) in aqueous solution • Bases • Yield hydroxide ions (OH-)in aqueous solution H+is also called a “proton” because a Hydrogen atom without its electron is just a proton (it has no neutrons) Svante Arrhenius (1859 - 1927)

  5. HCl (aq) → H+ (aq) + Cl– (aq) H+is responsible for acidicproperties OH- is responsible for basicproperties NaOH (aq) → Na+ (aq) + OH– (aq)

  6. Lowry Bronsted What about ammonia (NH3) Bronsted? It acts as a base, but doesn’t have OH-. 2. The Bronsted-Lowry Theory 20 years later: I guess we need I new definition for acid and base, Lowry! • Acids • proton (H+) donor • Base • proton (H+) acceptor

  7. Base is a proton (H+) acceptor: NH3 (g) + H2O(l) H+ Ammonia accepts a proton from water: NH4+(aq) + OH-(aq) donor acceptor Follow the Hydrogen ion – who donated it, who accepted it.

  8. Acids is a proton (H+) donor: H+ Hydrochloric acid donates a proton to water: HCl(g) + H2O(l) H3O+(aq) + Cl-(aq) donor acceptor H+ H2O H3O+ ion called the hydronium ion H3O+ splits apart quickly, so H3O+ and H+ are written interchangeably.

  9. HCO3-+ OH- HCO3- + H2O Amphoteric: a substance which can act as either an acid or a base. H+ H+ As you just saw, water is amphoteric. Bicarbonate ion is also amphoteric. CO32- + H2O donor acceptor H2CO3 + OH- acceptor donor

  10. Transition metal ions with charges of 2+ or 3+, create an acidic solution with water. Step 1: Formation of a hydrate. Water’s electrons are attracted to the BIG positive charge on Fe

  11. Step 2: Loss of H+ making acidic solution. Fe(H2O)63+ + H2O  H3O+ + Fe(H2O)5(OH)2+ H+ H All electrons are attracted inwards, so Hydrogenion has nothing to lose and leaves

  12. 3. Gilbert Lewis Definition CH3COO-(aq) + H2O(l) OH-(aq) + CH3COOH (aq) • Acids Base • electron acceptor ●electron donor H+ acid base What about those metals? I think we need a broader definition? Negative ions have extra electrons to donate to the lonely H+

  13. NH3 (g) + H2O(l) Conjugate acidis what remains after a base has accepted a proton. Conjugate base is what remains after the acid has donated its proton. NH4+(aq) + OH-(aq) Con. base Con. acid acid base You are looking at the forward and reverse reactions – which compound donates for which direction?

  14. B+ H2O HA+ H2O Each is called a conjugate pair. BH+ + OH- Con. base Con. acid acid base These are generic equations for an acid or base reaction H3O+ + A- Con. acid Con. base base acid

  15. CAN YOU / HAVE YOU? • Outline the historical development of acid base theories. • Include: Arrhenius, Bronsted-Lowry, Lewis • Write balanced acid/base chemical equations. • Include: conjugatepairs, amphoteric Additional KEY Terms Hydroxide Hydronium

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