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chem lecture ch16
Question | Answer |
---|---|
equilibrium law | Ka=[H+][A-]/[HA] ; or pKa = - log Ka |
acid ionization constant | Ka. For weak acids, Ka is small. The strength of an acid is expressed by Ka; the larger the value of Ka, the stronger and more fully dissociated the acid is. At the same time, the stronger the acid, the smaller the pKa. |
base ionization constant | Kb= [BH+][OH-]/B ; or pKb = - log Kb |
Percentage ionization | =(Moles ionized per liter/ moles available per liter) *100 |
1st and 2nd Acid-base properties of a salt | 1. Neither cation nor anion can affect the pH, solution should be neutral 2. Only cation of salt is acidic. solution will be acidic. |
3rd and 4th Acid-base properties of a salt | 3. Only the anion of the salt is basic, the solution will be basic. 4. If the cation is acidic and the anion is basic, the pH of the solution is determined by the relative strength of the acid and the base based on the Ka and the Kb of the ions. |
Buffer solutions | solutions that contain a weak acid and a weak base. They resist large changes of the pH-value when small amounts of strong acids or strong bases are added. |
Buffer work by...? | neutralizing large changes of the pH-value when small amounts of strong acids or strong bases are added. |
how do you calculate the pH-value of a buffer solution? | the same principles as before are employed for weak acids and bases. Either Ka or Kb can be used. |
Henderson-Hasselbalch equation | pH = (pKa + log)*([HA]/[A-]) |
formulas for The H+ concentration of a buffer | [ H+ ] = Ka *[HA]/[A] ; [ H+ ] = Ka*[mol HA]/ [mol A-] |