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ACIDS AND BASES

ACIDS AND BASES. Ionization of Water. Describe the relationship between the hydronium and hydroxide ion concentrations in water Include: the ion product of water, K w. Additional KEY Terms. Water is amphoteric. H +. HA + H 2 O ( l ) H 3 O + ( aq ) + A¯ ( aq )

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ACIDS AND BASES

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  1. ACIDS AND BASES Ionization of Water

  2. Describe the relationship between the hydronium and hydroxideionconcentrations in water • Include: the ion productof water, Kw Additional KEY Terms

  3. Water is amphoteric H+ HA + H2O(l) H3O+(aq) + A¯(aq) or B + H2O(l) BH+(aq) + OH¯(aq) H+

  4. Water particles collide - ions form • Water also dissociates into ions - self-ionization H2O(l) + H2O(l)H3O+(aq) + OH¯(aq) H2O(l) H+(aq) + OH¯(aq)

  5. Water reaches equilibrium with its ions ion product for water, Kw H2O(l) H+(aq) + OH¯(aq) KW = [H+][OH¯] KW = [H3O+][OH¯]

  6. At room temperature: Kw = [H+][OH-] = 1.00 x 10-14 Water is neutral - these ions must be a 1:1 ratio [H+] = [OH-] = 1.00 x 10-7 M Like all constants, the value of Kw varies with temperature.

  7. Like any reversible reaction, Le Chatelier's applies: OH- H+ + H2O Add a SB – increase [OH-] decrease [H+] Add a SA – increase [H+] decrease [OH-] This means that H+and OH¯ are BOTH present in any solution - whether they are acidic or basic. Kw = [H+][OH-] = 1.00 x 10-14

  8. n V 2.5 mol = 0.50 mol/L 5.0 L If 2.5 moles of hydrochloric acid is dissolved in 5.0 L of water, what is the [hydroxide ions]? HCl (s) H+(aq) + Cl¯(aq) M = Since HCl is a strong acid (100% dissociation): [H+] = 0.50 M

  9. How does the addition of HCl affect WATER’s equilibrium? Kw = [H3O+] [OH-] Amount contributed by self-ionization of water H2O(l) H+(aq) + OH¯(aq) 1.0 x 10-14 = [OH-] [0.50 ] + 1.0 x 10-7] [OH-] = 2.0 x 10-14 M

  10. 0.40 g of NaOH is dissolved in water to make a solution with a volume of 1.0 L. What is the hydronium ion concentration in this solution? NaOH (s) Na+(aq) + OH¯(aq) NaOH = 40.0 g/mol 0.40 g 1 mol = 0.010 M 1 L 40.0 g Since NaOH is a strong base(100% dissociation): [OH-] = 0.010 M

  11. How does addition of NaOH affect WATER’s equilibrium? Kw = [H3O+] [OH-] 1.0 x 10-14 = [H3O+] [0.010 ] + 1.0 x 10-7] [H+] = 1.0 x 10-12 M

  12. H2O(l) H+(aq) + OH¯(aq) KW = [H+][OH¯] = 1.00 x 10-14 Add a SA – increase [H+] decrease [OH-] Add a SB – increase [OH-] decrease [H+]

  13. CAN YOU / HAVE YOU? • Describe the relationship between the hydronium and hydroxideionconcentrations in water • Include: the ion productof water, Kw Additional KEY Terms

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