Acids & Bases

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A level Chemistry Mind Map on Acids & Bases, created by elishamjones on 10/27/2014.
elishamjones
Mind Map by elishamjones, updated more than 1 year ago
elishamjones
Created by elishamjones over 10 years ago
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Resource summary

Acids & Bases
  1. Bronsted-Lowry
    1. Acid = proton, H+, donator
      1. Base = proton, H+, acceptor
        1. Strong acids/bases fully ionised in aq solutions
          1. HCl, H₂SO₄, HNO₃ NaOH, KOH
          2. Weak acids/bases partially ionised in aq solutions
            1. Ethanoic acid Aqueous ammonia
              1. Equilibrium to the left
              2. Monoprotic = donates 1 H⁺ per molecule Diprotic = donates 2 H⁺ per molecule
              3. pH = -log₁₀[H⁺]
                1. [H⁺] = 10⁻ᵖᴴ
                  1. pH of strong acids & alkalis mixtures can be calculated

                    Annotations:

                    • You need to:  1) Work out moles for each reactants 2) Find the moles of the excess reactant 3) Use c = 1000n ÷ v where N is the moles of excess and V is the total volume  4) If the acid is in excess, use c to find pH. If the alkali is in excess, use  [H⁺] = Kw ÷ [OH⁻] and then find pH. 
                  2. 298K (25℃) Kw = 1x10⁻¹⁴ mol²dm⁻⁶
                    1. H₂O can be a acid or base
                      1. Temp increases, Kw increases
                        1. Shifts equilibrium to right
                        2. H₂O ⇌ H⁺ + OH⁻ ΔH = +ve
                          1. Kw = [H⁺] [OH⁻]
                            1. [H⁺] = √Kw

                              Annotations:

                              • Use this if you need: 1) To find [H⁺] in water at 298K 2) To find the pH of water at 298K
                              1. [H⁺] = Kw [OH⁻]

                                Annotations:

                                • Use this if you need: 1) To find pH of strong bases at 298K 2) To find conc of a strong base, rearrange to [OH⁻] = Kw ÷ [H⁺] 
                            2. Weak acids
                              1. HA ⇌ H⁺ +A⁻ ΔH = +ve
                                1. Temp changes rate of dissociation
                                  1. Equilibrium constant is Ka
                                    1. Ka = [H⁺] [A⁻] [HA]
                                      1. mol dm ⁻³
                                        1. Larger Ka = Stronger acid
                                          1. Temp increases, Ka increases
                                            1. If acid is 50% ionised, Ka = [H⁺]
                                              1. [H⁺] = √Ka x [HA]

                                                Annotations:

                                                • Use when you have a concentration of a weak acid and a Ka constant
                                                1. [H⁺] = Ka x [HA] ÷ [A⁻]

                                                  Annotations:

                                                  • Use when there is a mixture of excess weak acid and strong alkali
                                                2. p Ka = -log₁₀Ka

                                                  Annotations:

                                                  • Use this when you are not given a concentration for the weak acid and so can't use [H⁺] = √Ka x [HA]
                                              2. pH of weak acids & strong alkalis mixtures can be calculated

                                                Annotations:

                                                • You need to (if acid is excess):  1) Work out moles for each reactants 2) Find the moles of the excess reactant 3) Find the amount of [A⁻] formed. This is just the same as the moles of alkali added 4)  Use  [H⁺] = Ka x [HA] ÷ [A⁻] and then find pH. 
                                                • You need to (if alkali is excess):  1) Work out moles for each reactants 2) Find the moles of the excess reactant 3) Use c = 1000n ÷ v where N is the moles of excess and V is the total volume  4) If the alkali is in excess, use [H⁺] = Kw ÷ [OH⁻] and then find pH. 
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