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Chapter 9: ACIds , bases, and SALTS

Chapter 9: ACIds , bases, and SALTS. Bell Ringer. Name 1 acid and 1 base you have in your home. Use your book if you need help!. sECTION 1: acids, bases, and pH. Acids. Acid – any compound that increases the number of hydronium ions when dissolved in water

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Chapter 9: ACIds , bases, and SALTS

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  1. Chapter 9: ACIds, bases, and SALTS

  2. Bell Ringer • Name 1 acid and 1 base you have in your home. Use your book if you need help!

  3. sECTION 1: acids, bases, and pH

  4. Acids • Acid – any compound that increases the number of hydronium ions when dissolved in water • Hydronium ions – H3O+ form when H+ ions attach to water • Indicator – a compound that can reversibly change color depending on conditions, such as pH

  5. Acids • Properties • Taste sour • Cause indicators to change color • Conduct electric current • Corrosive • Damage materials

  6. Acids • Strong acids ionize completely • Charged ions then free to move around the solution and conduct electricity • Electrolyte – a substance that dissolves in water to give a solution that conducts an electric current

  7. Acids • Weak acids do not ionize completely • Some of the molecule dissociates to form ions, and then some ions form the molecule • Weak electrolytes

  8. Bases • Base – any compound that increases the number of hydroxide ions when dissolved in water • Properties • Bitter taste • Feel slippery • Conduct electric current • Cause indicators to change color • Can damage skin

  9. Bases • Strong bases are ionic compounds that contain a metal ion and a hydroxide ion • NaOH Na+ + OH– • Weak bases do not completely dissociate to form ions • Weak electrolytes

  10. pH • Indicates the concentration of H3O+ ions • pH – a value that is used to express the acidity or basicity of a system; each whole value on the scale indicates a ten fold change in acidity • Neutral = 7 • Acidic < 7 • Basic > 7

  11. sECTION 2: Acid-Base Reactions

  12. Acid-Base Reactions • Neutralization reaction is the reaction between an acid and a base • Forms water and a salt • Is a reaction between ions

  13. Acid-Base Reactions • A strong acid ionizes completely in solution. HCl + H2O Cl– + H3O+ • A strong base ionizes completely in solution. NaOH Na+ + OH– • The total neutralization reaction is the following: Cl– + H3O+ + Na+ + OH– Na+ + Cl– + 2H2O **In this reaction, Na and Cl are spectator ions, because they are like spectators watching the reaction that forms water. **If equal concentrations and volumes of a strong acid and a strong base are mixed, all hydronium and hydroxide ions react to form water, so solution is neutral

  14. Acid-Base Reactions • Form salt and water • Salt: an ionic compound that forms when a metal atom or a positive radical replaces the hydrogen of an acid • Neutral solutions are not always formed!! • Final pH depends on: • Amounts of acids and bases combined and how strong they are

  15. Acid-Base Reactions • Titration: the process of adding carefully measured amounts of one solution to another solution • equivalence point: the point when the original amount of acid equals the original amount of base added • strong acid with a strong base, equivalence point = pH 7 • strong acid with a weak base, equivalence point < pH 7 • strong base with a weak acid, equivalence point > pH 7

  16. Graphing Skills Interpreting Titration Curves Hydrochloric acid, HCl, was titrated with potassium hydroxide, KOH. How many moles of KOH were added to reach the equivalence point?

  17. Salts • Can be any combination of cations and anions, except hydroxides and oxides • Many uses • Table salt, baking soda • Used to clean, de-ice, chalk • Important in the body

  18. sECTION 3: acids, bases, and Salts in the home

  19. Cleaning Products • Cleaning products improve water’s ability to clean because they help water mix with oily substances • Soap – a substance that is used as a cleaner and dissolves in water • Can dissolve both oil and water • Allows water and oil to form an emulsion that can be washed away by rinsing

  20. Cleaning Products • Soap does not work well in hard water (water that contains dissolved cations) • These cations combine with soap to form soap scum • Detergents- water soluble cleaner that can emulsify dirt and oil • Salts of sodium, potassium, etc..

  21. Cleaning Products • Ammonia used often to clean • Weak base because it ionizes only slightly • Good for cleaning away light grease smears (fingerprints) • Bleach – chemical compound used to whiten or make lighter (basic) • Disinfectant – chemical substance that kills harmful bacteria or viruses

  22. Personal-Care and Food • Many healthcare products are acids or bases • Vitamin C is acid • Antacids – weak bases that neutralize stomach acid • Shampoos have a pH between 5 and 8 • Acids used as antioxidants • Antioxidants prevent oxygen from reacting with molecules • Used in the kitchen

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