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Flashcards

pH

Mary Doria A2 chemistry A-Level English 47 cards

Calculating weak acid?

Cards in this deck (47)

  1. 1Bronsted-Lowry acidproton donor
  2. 2Bronsted-Lowry baseProton acceptor
  3. 3What is a monobasic acidThis is when each molecule can release 1 proton
  4. 4What is a di-basic acid?This is when each molecule can release 2 protons. For example:
    H2SO4 --> H+ + HSO4-
    HSO4- <--> H+ + SO4-
  5. 5what is a tri-basic acid?This is when each molecule can release 3 protons.
  6. 6Neutralisationa chemical reaction in which an acid and a base react together to produce salt and water.
  7. 7why are state symbols important in ionic equations?-ions are dissociated only in solution, so a solid ionic compound is shown undissociated.
  8. 8what are the products when you react acid and carbonate?salt, carbon dioxide and water
  9. 9what are reactants to salt and water?-Acid + base
    OR
    -Acid + alkali
  10. 10What happens when an acid is added to water?This releases a proton from an acid. For example, HCl. This creates a hydronium ions and forms a dative covalent bond.
  11. 11Acid-base pair?A pair of two species that transform into each other by gain and loss of a proton.
  12. 12calculating pH?-log[H+(aq)]
  13. 13calculating [H+(aq)]?10^ -pH
  14. 14when there is a low pH value, what is the amount of [H+(aq)]?large
  15. 15Strong acid?An acid that completely dissociates in solution
  16. 16Weak acid?An acid that partially dissociates in solution
  17. 17how do you calculate Ka?[H+(aq)][A-(aq)]
    ------------------
    [HA(aq)]
  18. 18what happens to the value of pKa, when there is a high value of Ka?Low
  19. 19calculate pKa?-logKa
  20. 20calculate Ka?10^ -pKa
  21. 21Calculating weak acid?Calculating weak acid?
  22. 22Ionic product of waterKw = [H+(aq)][OH- (aq)]
    Kw = 1 x 10^ -14
  23. 23What's the balance between H+ and OH- in an acidic solutions?H+ > OH-
  24. 24What's the balance between H+ and OH- in an alkaline solutions?H+ < OH-
  25. 25Calculating the pH of a strong base?Calculating the pH of a strong base?
  26. 26Buffer Solutiona mixture that minimises pH changes on addition of small amounts of acid or base
  27. 27What are the two features of a buffer solution?- a weak acid
    - its conjugate base
  28. 28—
  29. 29—
  30. 30—
  31. 31Calculate buffer solution using Ka to find pH-logKa + log([A-(aq)]/[HA(aq)]
  32. 32what is the equilibrium equation for blood?H2CO3(aq) ⇌ H+(aq) + HCO3-(aq)
  33. 33What happens when there is an increase H+ ion in the blood?The equilibrium will shift to the left. This will remove most of the H+ ions.
  34. 34If extra acid is produced in the blood, how do buffers prevent the pH from falling?An increase in H+ ions is removed by HCO3-, forming Carbonic acid (H2CO3). The carbonic acid is converted into aqueous CO2 by an enzyme. In the lungs, the dissolved CO2 is converted into CO2 gas, which is then exhaled.
  35. 35Equivalence pointThis is the point in a titration at which the volume of one solution has reacted with the volume of the second solution.
  36. 36What does a titration curve looks like?What does a titration curve looks like?
  37. 37Features of the titration curves-When the base is first added, the pH increases slightly - the acid is in excess
    -Then the pH increases sharply, there is only small excess of acid.
    -As further base is added, there is little addition change in pH - the base is now in great excess.
  38. 38What are the 3 indicators of pH and there colour?- Phenolphthalein (pinky-purple) - 9-10
    -Bromothymol blue (yellow-blue) - 6-7
    -methyl orange (orange-yellow) - 3-4
  39. 39which indicator is suitable when there is a strong acid and strong base?-phenolphthalein and methyl orangewhich indicator is suitable when there is a strong acid and strong base?
  40. 40which indicator is suitable when there is a strong acid and weak base?-methyl orange
    -NOT phenolphthalein    which indicator is suitable when there is a strong acid and weak base?
  41. 41which indicator is suitable when there is a weak acid and strong base?-phenolphthalein
    -NOT methyl orange    which indicator is suitable when there is a weak acid and strong base?
  42. 42which indicator is suitable when there is a weak acid and weak base?-There is no suitable indicatorswhich indicator is suitable when there is a weak acid and weak base?
  43. 43Standard enthalpy change of neutralisationthe energy change that accompanies the neutralisation of an aqueous acid by an aqueous base to form one mole of H2O(l), under standard conditions
  44. 44Why do we get the same value for the enthalpy chnage for neutralisation for different strong acids?This is because there are completely dissociated.
  45. 45Why do weak acids give a less exothermic value for the enthalpy change of neutralisation using strong acids?Weak acids are only partially dissociated.
    -Most of the weak acid molecules must first dissociate to release H+ ions and this process requires energy. Consequently, the enthalpy change us less exothermic.
  46. 46Calculating Qm x c x ΔT
    (its in Joules)
  47. 47Calculating enthalpy changeQ (convert it into KJ)
    -------------
    n (mols)

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A-Level A2 chemistry (Module 4 - Rates, equilibrium and pH) Flashcards on pH, created by Mary Doria on 16/02/2016.
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Mary Doria
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