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Titration Wrap-Up

Titration Wrap-Up. Strong vs. Weak Acids and Bases Titration Curves. Naming Acids and Bases. Strong acids. Acids can be strong or weak. Strong acids dissociate fully into solution, so that all their H + ions are released into the mixture. +. HA. H +. A –.

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Titration Wrap-Up

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  1. Titration Wrap-Up Strong vs. Weak Acids and Bases Titration Curves

  2. Naming Acids and Bases

  3. Strong acids Acids can be strong or weak. Strong acids dissociate fully into solution, so that all their H+ ions are released into the mixture. + HA H+ A– Hydrochloric acid is a typical strong acid, so the dissociation reaction is complete: + HCl H+ Cl–

  4. Weak acids Weak acids do not dissociate fully, some of their H+ ions stay attached to the acid molecule. The dissociation of a weak acid in water is a reversible reaction: ⇌ + HA H+ A– Ethanoic acid is a typical weak acid, with its ions in dynamicequilibrium with the un-dissociated acid. The reaction is moving both directions at the same rate. ⇌ + CH3COOH H+ CH3COO–

  5. Properties of strong and weak acids

  6. Strong or weak?

  7. pH of strong and weak acids pH is a measure of the number of H+ ions in solution, with a lower pH meaning more H+ ions. Because strong acids dissociate fully in solution, they contain more H+ ions per molecule of acid, producing a lower pH. Compared to weak acids of the same concentration, strong acids: • have lower pH values • are better conductors of electricity • react more quickly. high H+ low H+

  8. Strong Acids • HI • HBr • HCl • HNO3 • H2SO4 • HClO4 • HClO3

  9. Properties of strong and weak bases Bases can be classified as strong and weak in the same way as acids. A strong base, such as sodium hydroxide, fully dissociates in solution. + NaOH Na+ OH– A weak base, such as ammonia, does not fully dissociate, and some of the OH– ions are not released into solution. ⇌ + + NH3 H2O NH4+ OH– Comparable levels of ion dissociation mean that strong and weak bases have similar properties to strong and weak acids.

  10. Properties of strong and weak alkalis

  11. Strong Bases • NaOH • KOH • LiOH • RbOH • CsOH • Ca(OH)2 • Ba(OH)2 • Sr(OH)2

  12. Strong and weak acids and bases

  13. Titration Curves

  14. Titration & Titration Curves • Titration: the adding of one solution of an known concentration into another solution • standard solution: a solution with a known concentration • Titration curve: a graph showing pH vs volume of acid or base added • The pH shows a sudden change near the equivalence point • The Equivalence point (a.k.a. stoichiometric point) is the point at which the moles of OH- are equal to the moles of H3O+ • End point- Point at which titration is complete; indicator color change

  15. pH mL base added Strong acid-strong base Titration Curve • At equivalence point, Veq: Moles of H3O+ = Moles of OH- • There is a sharp rise in the pH as one approaches the equivalence point • With a strong acid and a strong base, the equivalence point is at pH =7

  16. Weak acid-strong base Titration Curve • The increase in pH is more gradual as one approaches the equivalence point • With a weak acid and a strong base, the equivalence point is higher than pH = 7

  17. Indicators

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