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Acids and Bases

Acids and Bases. Unit Main Goals. Definitions (3) Properties Using pH Neutralization. Malic Acid. Acetic Acid. Citric Acid. Malic Acid. Carbonic Acid. Lactic Acid. Hydrochloric Acid. But, what are ACIDS?. Acid Properties.

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Acids and Bases

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  1. Acids and Bases

  2. Unit Main Goals • Definitions (3) • Properties • Using pH • Neutralization

  3. Malic Acid Acetic Acid Citric Acid Malic Acid Carbonic Acid Lactic Acid Hydrochloric Acid But, what are ACIDS?

  4. Acid Properties • Taste sour (like lemons) (AHH!!! Don’t try this at home!) Often Corrosive and/or Poison!!! • React with most metals to form hydrogen gas2Zn(s) + 2HCl(aq) ---> ZnCl + H2 • Frequently feel "sticky" • Conduct electric current (ELECTROLYTE) • Form ions in solution • Change blue litmus paper Red

  5. Base Properties • Taste bitter (like baking soda) (AHH!!! Don’t try this at home either!) Often Caustic and/or Poison!!! • Frequently feel "slippery" (like soap) • Conduct electric current (ELECTROLYTE) • Form ions in solution • Change red litmus paper to Blue • React with Oils & Greases BASIC BLUE

  6. Simple Test BASIC ACIDIC NEUTRAL LITMUS PAPER Why must you test with both?

  7. Spectrum of Solutions • Acids Neutrals Bases

  8. Hydrogen Ion 1e- 1 p+ 1 p+ Hydrogen Atom Hydrogen Ion PROTON All Acids will have a hydrogen in their chemical formula

  9. Arrhenius Definition • Acid - Substances in water that increase the concentration of hydrogen ions (H+). • HCL(aq) • NaOH(aq) • Base - Substances in water that increase concentration of hydroxide ions (OH-). • By definition – easy to sort substances into acids and bases • Problem – many bases do not actually contain hydroxides • H+ • Cl- • Na+ • OH-

  10. HCL(aq) • H+ • Cl- • HCl<---> H+ + Cl- IN WATER • HCl + H2O<---> H3O+ + Cl- HYDRONIUM Ion

  11. Brønsted-Lowry Definition • Acid - Substances that donate protons (H+). • Base - Substances that accept protons . (Must have a negative pole somewhere to attract those positives!!) Arrhenius Definition • Acid - Substances in water that increase the concentration of hydrogen ions (H+). • Base - Substances in water that increase concentration of hydroxide ions (OH-). Isn’t that the same thing??

  12. Brønsted-Lowry Definition Become Negative • Acid - Substances that donate protons (H+). • Base - Substances that accept protons . (Must have a negative pole somewhere to attract those positives!!) Become Postive Lewis Definition Become Negative • Acid - Substances that accept electrons. • Base - Substances that donate electrons. Become Positive

  13. Summary • If you've got something that can give off H+, it's an acid.  • All acids you'll see have hydrogen atoms in them.  • Most common acids have the letter H in the beginning of their formula • Exception: acetic acid CH3COOH •  Bases, on the other hand, are compounds that give off OH- in water or accept protons or donate electrons  •  Most common baes have an "OH" in the end of their formula.  • Exception: ammonia, NH3.

  14. Conjugates HF(aq) + H2O(l) <---> F-(aq) + H3O+(aq) Base Acid Conjugate Base Amphoteric NH3(aq) + H2O(l) <---> NH4+(aq) + OH-(aq) Acid Base Conjugate Acid

  15. Ways to Test • Litmus Paper • Phenolphthalein Indicator • Golden Rod Paper • Cabbage Juice • pH paper

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