Chem 15.7-15.8

150 0 0 change equilibrium 3 strong bases all strong

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Unformatted text preview: H3O+ Kw = 1.0 x 10- 14 3 Find the pH of a mixture of 0.150 M HF(aq) solu@on and 0.100 M HClO2(aq) Write the reactions for the acids with water and determine their Kas HF + H2O ⇔ F− + H3O+ Ka = 3.5 x 10- 4 HClO + H2O ⇔ ClO− + H3O+ Ka = 2.9 x 10- 8 H2O + H2O ⇔ OH− + H3O+ Kw = 1.0 x 10- 14 If the Kas are sufficiently different, use the strongest acid to construct an ICE table initial for the reaction Enter the initial concentrations – assuming the [H3O+] from water is ≈ 0 [HF] [F-] [H3O+] 0.150 0 ≈0 change equilibrium 3 Strong Bases • All strong bases for this class contain the OH- ion (NaOH, Mg(OH)2, etc.) • Recall: Polypro4c acids dissociate in two steps – H2SO4 → H+ + HSO4- ⇌ H+ + SO42- – Ka,1 > Ka,2 (i.e. the first dissocia4on is stronger than the second) • “polyhydroxyl” bases dissociate in one complete step – Mg(OH)2 → Mg2+ + 2 OH- – No difference in the Kb of the 2 hydroxyls • 0.025 M Ca(OH)2 yields 0.050 M OH- – pOH = - log (0.050) = 1.30 – pH = 14.00 - 1.30 = 12.70 A solu4on of Mg(OH)2 has a pH of 11.92. What is the concentra4...
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