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8.1 Acids and Bases

8.1 Acids and Bases. Characteristics of Acids. Acids ( ie HCl , H 2 SO 4 , HCH 3 COO): a re electrolytes react with many metals to form hydrogen gas and a salt. cause indicators to turn colour - b lue litmus turns red - p ink p henophthalein goes colourless neutralize bases.

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8.1 Acids and Bases

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  1. 8.1 Acids and Bases

  2. Characteristics of Acids • Acids (ieHCl, H2SO4, HCH3COO): • are electrolytes • react with many metals to form hydrogen gas and a salt. • cause indicators to turn colour - blue litmus turns red - pinkphenophthalein goes colourless • neutralize bases

  3. Characteristics of Bases • Bases (ieNaOH, Ca(OH)2, NH3 or NH4OH(aq)): • are electrolytes • form when active metals react with water • cause indicators to turn colour - red litmus turns blue - colourlessphenophthalein goes pink • neutralize acids

  4. The Arrhenius Theory of Acids and Bases Science cracks me up! • Svante Arrhenius (1859-1927) -his theory described the activity of acids and bases when they were dissolved in water.

  5. Acids ionize to form H+ ions in aqueous solution examples: HCl(aq)H+(aq) + Cl-(aq) H2SO4(aq) 2H+(aq) + SO42- (aq) The Arrhenius Theory of Acids and Bases

  6. Bases dissociate to form OH- ions in aqueous solution examples: NaOH(aq) Na+(aq) + OH-(aq) Mg(OH)2(aq) Mg 2+(aq) + 2OH-(aq) The Arrhenius Theory of Acids and Bases

  7. Acid strength is determined by the concentration of H+ ions in solution. (high concentration of H+ ions in solution, means a stronger acid) Base strength is determined by the concentration of OH- ions in solution. (high concentration of OH- ions in solution, means a stronger base) What factors affect Acid and Base strength?

  8. The most important factor is the degree of ionization or dissociation of the acid or base Not all Acids and Bases are strong, for instance: A 1.00M HCl solution is a strong acid; A 1.00M HF solution is a weak acid. A 1.00M NaOH solution is a strong base; A 1.00M NH4OH solution is a weak base. What factors affect Acid and Base strength? Remember: M = mol/L

  9. Ionize 100% (>99%) upon dissolving in water. Because the acid ionizes 100%, the concentration of H+ is the same as the concentration of the acid. (i.e. a 1.00M solution of HCl has an [H+] of 1.00M) HCl, HBr, HClO4, H2SO4, HNO3, HI are strong acids Note: [ ] = the concentration of Strong Acids

  10. Ionize much less than 100% upon dissolving in water (less than 5%) the concentration of H+ is much less than the concentration of the acid (i.e. a 1.00M solution of HCH3COOH has a [H+] less than 1.00M) examples include all of the other acids Weak Acids Note: Acid Strength is not related to reactivity. HF is a weak acid, but it consumes flesh and bone.

  11. dissociate 100% upon dissolving in water the concentration of OH- is the same as the concentration of the base (i.e. a 1.00M solution of NaOH has a [OH-] of 1.00M) examples include hydroxides of Group 1 metals and Group 2 metals below beryllium. Strong Bases

  12. Dissociate much less than 100% upon dissolving in water (less than 5%) Because of this, the concentration of OH- is much less than the concentration of the base (i.e. a 1.00M solution of NH4OH has a [OH-] less than 1.00M) examples include all of the other bases Weak Bases

  13. 8.2 pH of a Solution • pH is a way of indicating the concentration of H+ ions present in a solution • pH = Power of Hydrogen

  14. Calculating Ion Concentration and pH [H+] = 10-pH pH = -log [H+]

  15. pH and Ion Concentration

  16. pH Scale

  17. READ pg. 362 – 367 ANSWER # 1 – 3, 6, 7 on pg. 367 READ pg. 368 – 374 ANSWER # 1 – 6 on pg. 375 HOMEWORK

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