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Acids and Bases: Experimental Definitions

Acids and Bases: Experimental Definitions. Acids : Taste sour. Turn litmus red . React with active metals to release hydrogen gas. React with bases to form water and a salt. Acids and Bases: Experimental Definitions. Bases : Taste bitter. Turn litmus blue . Feel slippery.

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Acids and Bases: Experimental Definitions

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  1. Acids and Bases: Experimental Definitions Acids: • Taste sour. • Turn litmus red. • Reactwith active metals to release hydrogen gas. • React with bases to form water and a salt.

  2. Acids and Bases: Experimental Definitions Bases: • Taste bitter. • Turn litmus blue. • Feelslippery. • React with acids to form water and a salt.

  3. Acids and Bases: Experimental Definitions

  4. Acids, Bases, and Salts Arrhenius Theory Acid: A molecular substance that ionizes in aqueous solution to form hydrogen ions (H+).

  5. Acids, Bases, and Salts Arrhenius Theory Base: A substance that produces hydroxide ions (OH-) in aqueous solution.

  6. Acids, Bases, and Salts Neutralization: When an acid reacts with a base, the properties of each are neutralized and the products are water and a salt. Acid + Base → Water + Salt

  7. Acids, Bases, and Salts Limitations of the Arrhenius Theory • H+ ions do not exist in water solution. Protons react with water to form hydronium ions (H3O+). H+ + H2O → H3O+ • The Arrhenius theory does not explain the basicity of ammonia and similar compounds. • It only applies to reactions in aqueous solution.

  8. Acids, Bases, and Salts Brønsted-Lowry Theory Acid: Proton donor HCI + H2O → H3O+ + CI- Base: Proton acceptor NH3 + H2O → NH4+ + OH-

  9. Acids, Bases, and Salts Brønsted-Lowry Theory

  10. Acids, Bases, and Salts Salts are ionic compounds composed of cations other than hydrogen and anions other than hydroxide.

  11. Acids, Bases, and Salts Anhydride means without water. Nonmetal oxides are acidic anhydrides. SO3 + H2O → H2SO4

  12. Acidic and Basic Anhydrides Metal oxides are basic anhydrides. Example: Lime (calcium oxide) reacts with water to form slaked lime (calcium hydroxide). CaO + H2O → Ca(OH)2

  13. Strong and Weak Acids and Bases Strong acids ionize completely in water solution. HCl(aq) → H+(aq) + Cl-(aq) Weak acids only partially ionize in water solution. HCN(aq) ↔ H+(aq) + CN-(aq)

  14. Strong and Weak Acids and Bases Strong bases ionize or dissociate completely in water solution. NaOH(aq) → Na+(aq) + OH-(aq) Weak bases only partially ionize in water solution. NH3(aq) + H2O ↔ NH4+(aq) + OH-(aq)

  15. Strong and Weak Acids and Bases Ammonia accepts a proton from water, forming a basic solution.

  16. Neutralization The reaction of an acid with a base is called neutralization. Water molecules are the result of the reaction between hydrogen ions and hydroxide ions. H+ + OH-↔ H2O

  17. Neutralization During neutralization, an acid reacts with a base, forming water and a salt.

  18. Neutralization The amount of acid (or base) in a solution is determined by careful neutralization.

  19. The pH Scale pH is a means of expressing the acidity or basicity of a solution.

  20. The pH Scale pH means “power” of hydrogen. pH = -log[H+]

  21. The pH Scale

  22. Buffers and Conjugate Acid-Base Pairs Conjugate acid-base pairsare compounds or ions that differ by one proton (H+). For example, the chloride ion (Cl-) is the conjugate base of the acid, hydrochloric acid (HCl).

  23. Buffers and Conjugate Acid-Base Pairs Buffer solutionscontain a weak acid and its conjugate base. Such solutions are capable of maintaining a nearly constant pH when small amounts of acid or base are added.

  24. Acid Rain Nonmetal oxides present in air react with water, forming acidic solutions. Rain with a pH of less than 5.6 is considered to be acid rain. Carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen monoxide (NO), and nitrogen dioxide (NO2) are the major nonmetallic oxides responsible for acid rain formation.

  25. Antacids: A Basic Remedy Hyperacidity is when the stomach secretes too much acid. Antacids are often taken to neutralize excess acid and reduce the symptoms of hyperacidity. Excessive use of antacids can lead to an increase in the pH of blood, a condition known as alkalosis.

  26. Antacids: A Basic Remedy

  27. Antacids: A Basic Remedy

  28. Acid Reducers Acid Reducers have been displacing antacids as a way to combat hyperacidity.

  29. Acids and Bases in Industry and at Home Sulfuric acid is the leading chemical substance produced in the U.S. It is used to manufacture fertilizers and industrial chemicals. It is the acid of automotive batteries. Production is 40 billion kg/year.

  30. Acids and Bases in Industry and at Home Hydrochloric acid has a number of uses. It is used as a rust remover, and it removes lime from mortar and household plumbing fixtures. It can be purchased from hardware stores as muriatic acid. Annual U.S. production is 4 billion kg.

  31. Acids and Bases in Industry and at Home Lime (CaO) is produced by heating limestone (CaCO3). CaCO3 + heat → CaO + CO2 Lime can be slaked by reacting with water to make calcium hydroxide (Ca(OH)2). Slaked lime is used to make mortar and cement and to sweeten soil. Annual U.S. production is 22 billion kg.

  32. Acids and Bases in Industry and at Home Soil can be “sweetened” by adding slaked lime [Ca(OH)2].

  33. Acids and Bases in Industry and at Home Sodium hydroxide, also known as lye, can be purchased for home use as oven cleaner or drain cleaners. It is used commercially to make soap. Annual U.S. production is 9 billion kg.

  34. Acids and Bases in Industry and at Home Ammonia is produced for use as fertilizer and in household cleaning products. Production is about 11 billion kg/year.

  35. Acids and Bases in Industry and at Home Concentrated acids and bases are corrosive to tissue and are health hazards. They can denature proteins in living cells. The human body has wonderful mechanisms for maintaining the proper pH of tissue, blood, and body fluids.

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