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Chapter 18 Acids, Bases & Salts PowerPoint Presentation
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Chapter 18 Acids, Bases & Salts

Chapter 18 Acids, Bases & Salts

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Chapter 18 Acids, Bases & Salts

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  1. Chapter 18 Acids, Bases & Salts

  2. Properties of Acids • Homogeneous mixture • Sour, sharp, and tart taste • Conduct electricity – weak to strong electrolyte • React with metals and produces hydrogen gas • produce hydrogen ion (H+) when dissolved in water *H+ + H2O → H3O+ (hydronium ions) *H+ is also called proton. Why? • The formulas usually start with hydrogen (Ex) HCl, H2SO4, HCN, HNO3, CH3COOH = HC2H3O2

  3. Bases • Bitter taste and slippery feel • Homogeneous mixture • Conduct electricity – weak to strong electrolyte • Alkali is another name for bases • Many base substances have OH- ions • When an alkali dissolves in water, the solution is basic or alkaline • React with acid to form water and salt (Ex) HCl (aq) + KOH(aq) → H2O (l) + KCl(aq) salt

  4. Indicator • indicates if a solution is acidic or basic • common indicators

  5. Three Definitions of Acids-Bases • Arrhenius • BrØnsted-Lowry • Lewis

  6. Definitions of Acids and Bases *H+ion always combines with water molecule, forming hydroniumion, H3O+

  7. Arrhenius Acids: HCl, HC2H3O2, HCN • Arrhenius Bases: NaOH, Ca(OH)2 • BrØnsted-Lowry Acids and Bases: can only be determined from chemical equations H2O + HCl→ H3O+ + Cl- base acid

  8. Terms related Acids • Amphoteric: Ions or molecules that can become an acid anda base (Ex) HSO4- + H2O → SO42- + H3O+ acid base HSO4- + H2O → H2SO4 + OH- base acid • Oxyacids: acids containing oxygen (Ex) HNO3, H2SO4, HClO

  9. Monoprotic Acids • Have one proton (H+) to donate (Ex) HCl, HNO3, HI, HClO3 • Diprotic Acids • Have more than two protons to donate (Ex) H2SO4 • Triprotic Acids • Have three protons to donate (Ex) H3PO4

  10. Conjugate Acid-Base Pair • An acid and a base that only differ by one H+ ion • Always made of one reactant and one product • Often in reversable reactions (Ex) HSO4- + H2O ↔ SO42- + H3O+ acid base base acid HSO4- + H2O ↔ H2SO4 + OH- base acid acid base

  11. Strong vs. Weak • Strong: 100% dissociation of H+ or OH– • Strong electrolytes (conduct electricity very well) • Weak: Less than 100% dissociation of H+ or OH– • Weak electrolytes (conduct electricity somewhat) • Examples • Strong acids: H+7A, H2SO4, HClO4, HNO3 • Strong bases: 1A+OH, Sr(OH)2, Ba(OH)2 • Weak acids: HCN, HC2H3O2 • Weak bases: NH3 (ammonia) = NH4OH (ammonium hydroxide)

  12. Acid-Base Reactions • Reaction between an acid and a base HA + BOH → H2O + BA HA = general form of acid BOH = general form of base BA = a salt (not always table salt) (Ex) HCl + NaOH→ (Ex) H2SO4 + KOH → • Always produce water and a salt • A double-displacement reaction • Also called neutralization reaction

  13. Salts • Neutral salt • Formed from a strong acid and a strong base • Neither acidic nor basic (pH = 7) (Ex) HCl + NaOH→ NaCl + H2O • Basic salt • Formed from a strong base and a weak acid • pH > 7 (Ex) NaOH + HC2H3O2→ NaC2H3O2 + H2O • Acidic salt • Formed from a strong acid and a weak base • pH < 7 (Ex) HCl + NH4OH → NH4Cl + H2O