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ACIDS AND BASES

ACIDS AND BASES. Define electrolyte and explain the association with weak and strong. Explain the difference between weak and strong acid and base. Explain and compare dilute and concentrated solutions of acid or base. HA + H 2 O . B + H 2 O . H 3 O + + A -.

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ACIDS AND BASES

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  1. ACIDS AND BASES

  2. Define electrolyte and explain the association with weak and strong. • Explain the difference between weak and strong acid and base. • Explain and compare dilute and concentrated solutions of acid or base.

  3. HA+ H2O B+ H2O H3O+ + A- Con. acid Con. base base acid BH+ + OH- Con. base Con. acid acid base

  4. For a solution to conduct an electric current, charged particles or ions must be present in the solution.

  5. Electrolytes - conduct an electric current when in aqueous solution or when in a molten state. All ionic compounds act as electrolytes (as do highly polar molecular compounds). Most molecular compounds are non-electrolytes. NaCl(s) Na+(aq) + Cl–(aq) C11H22O11(s) C11H22O11(aq) electrolytes non-electrolytes

  6. Only hydrogens in very polar bonds are ionizable. (H must be bonded to a very electronegative element). H - + + δ+ H Cl δ- O H H δ- δ+ C H C H H + +

  7. A (s) B+(aq) + C–(aq) Electrolytes are classified as strong and weak. Strong: produces many ions in solution - dissociates 100% in water. (NaCl) Weak: partially dissociates. Usually weak polar molecules. (household vinegar)

  8. polar ionic

  9. ionic polar

  10. HCl (s) H+(aq) + Cl-(aq) water Strong acids easily donate protons - completelydissociate or ionize. Strong acids are strong electrolytes. Indicate complete dissociation using single arrow. [HCl]i = [H+]e= [Cl-]e

  11. Weak acids are weak electrolytes. Weak acids incompletely ionize. Equilibriumbetween the ions and the molecules of acid. HC2H3O2+ H2O H3O+ + C2H3O2- acetic acid The reverse reaction is favored over the forward one. The ions formed react very easily to reform the acid and the water.

  12. NaOH (s) Na+(aq) + OH-(aq) water Strong bases are strong electrolytes. Strong bases dissociate into OH¯, or oxide, (O-2). Indicate complete dissociation using single arrow. [NaOH]i= [Na+]e= [OH-]e

  13. Basically, any hydroxide and Alkali (1A) or Alkali-Earth Metal (2A) would be a strong base because of 100% dissociation.

  14. NH3(g) + H2O (l) NH4+(aq) + OH-(aq) Weak bases are poor proton acceptors. Incompletely dissociate - form an equilibrium between the molecule and the ions formed. Does not produce hydroxide ions readily. The reverse reaction is favored.

  15. Common weak bases are usually conjugate bases of strong acids. weak HA+ H2O H3O+ + A- Con. acid Con. base base acid In fact: The weaker the acid, the stronger its conjugate base. The weaker the base, the stronger its conjugate acid.

  16. Acid Strength Table

  17. Any acid that contains only one ionizable hydrogen is called monoprotic. Contains two ionizable hydrogens - diprotic Three - triprotic H O O H H s O O H Cl O p s O H O O H Phosphoric acid Sulfuric acid

  18. Acid Strength Table

  19. The equilibrium reaction favours the strongest acid.

  20. HCO3– + PO43– Which direction is favoured and why? fwd reaction is favoured HCO3–is the stronger acid

  21. Don't confuse weak and strong with dilute and concentrated. Weak and strong indicates the proportionof an acid or base which ionized. Dilute and concentrated refer only to the volume of acid and base dissolved in a total solution volume. It is possible to have a concentrated weak acid/base or dilute strong acid/base

  22. Strong acids and bases are strong electrolytes. • Weak acids and bases are weak electrolytes. • Weak acids and bases partially ionize in water. • The stronger the acid, the weaker its conjugate base. • The stronger the base, the weaker its conjugate acid. • When acids and bases react, the stronger acid donates its proton and the stronger base accepts the proton.

  23. CAN YOU / HAVE YOU? • Define electrolyte and explain the association with weak and strong. • Explain the difference between weak and strong acid and base. • Explain and compare dilute and concentrated solutions of acid or base.

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