Acid and Bases

Descrição

Mapa Mental sobre Acid and Bases, criado por Amy Holden em 10-04-2015.
Amy Holden
Mapa Mental por Amy Holden, atualizado more than 1 year ago
Amy Holden
Criado por Amy Holden mais de 9 anos atrás
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Resumo de Recurso

Acid and Bases
  1. Acid-base theories
    1. Lewis
      1. Acid - electron pair acceptor
        1. Base - electron pair donor
        2. Bronsted-Lowry
          1. Acid - proton donor
            1. Base - proton acceptor
          2. Conjugate systems
            1. Acids are related to bases
              1. ACID <=> PROTON + CONJUGATE BASE
              2. Bases are related to acids
                1. BASE + PROTON <=> CONJUGATE ACID
                2. For an acid to behave as an acid, it must have a base present to accept a proton
                  1. acid + base <=> conjugate base + conjugate acid
                    1. HA + B <=> BH+ + A-
                3. pH = -log10[H+]
                  1. The smaller the pH, the greater the conc. of H+
                  2. pOH = -log10[OH-]
                    1. Kw = [H+][OH-]
                      1. water is weakly dissociated
                      2. Weak acids and bases
                        1. weak acids and weak bases dissociate only in aqueous solution
                          1. Ka = ([H+][A-]) / [HA]
                            1. Ka is the dissociation constant for a weak acid
                              1. Ka = [H+]2 / [HA]
                              2. The weaker the acid..
                                1. the less it dissociates
                                  1. the fewer ions you get
                                    1. the smaller Ka
                                    2. pKa
                                      1. very weak acids have very small Ka values
                                        1. Its is easier to compare the strength as pKa
                                        2. pKa = -log10 (Ka)
                                      2. species that can act as an acid or base are amphoteric
                                        1. Strong acids
                                          1. a strong acid is one which dissociates completely in water into H+ and A-
                                            1. Examples
                                              1. HCl
                                                1. HNO3
                                                  1. H2SO4
                                                  2. Strong acids do not dissociate fully at high concentrations
                                                    1. There is not enough water
                                                      1. diluting the acid tenfold causes the pH to increase by one unit
                                                    2. Titrations
                                                      1. Curves
                                                        1. Indicators
                                                        2. Buffers
                                                          1. A solution that resists change of pH when small amounts of acid or base are added or on dilution
                                                            1. Acidic buffers
                                                              1. They are made from a mixture of a weak acid and a soluble salt of that acid
                                                                1. It will maintain a pH of below 7
                                                                  1. The weak acid component is to act as a source of HA to remove any added OH-
                                                                    1. HA + OH- --> A- + H2O
                                                                    2. The salt component is to act as a source of A- to remove any added H+
                                                                      1. A- + H+ --> HA
                                                                    3. It is possible to saturate a buffer
                                                                      1. Basic buffers
                                                                        1. It will maintain a pH of above 7
                                                                          1. They are made from a mixture of a weak base and a soluble salt of that base
                                                                            1. Aqueous ammonia and ammonium chloride acts as a bsic buffer
                                                                              1. NH3 + H+ --> NH4+
                                                                                1. NH4+ + OH- --> NH3 + H2O

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