# SA/SB Titration SA/SB Titration Initial pH: pts A and E: A = all SA; B = all SB Pre-equiv: pts B and F: B = xs SA; F = xs SB Equiv pt: pt C: pH = 7 Post-equiv: pts D and G: D = xs SB; G = xs SA WA/SB Titration

Initial pH: pts A and E: A = all WA; B = all WB (ICE box) Pre-equiv: pts B and F: buffer (modified ICE) Equiv pt: pts C and G: switcheroo (use ICE for conjugate) Post-equiv: pts D and G: D = xs SB; G = xs SA WA/SB Problem

Titration of 40.0 mL of 0.100 M HPr (propanoic acid, CH3CH2CO2H) with 0.100 M NaOH. Ka HPr = 1.3x10-5 How many mL NaOH to reach equiv pt? Calc initial pH. pH for pre-equiv pt

Calc pH when add 10.0 mL of NaOH. pH at equiv pt = switcheroo Calc pH at equiv pt. pH post-equiv pt Calc pH when add 60.0 mL of 0.100 M NaOH.

Additional Problem Calculate pH for the titration of 25.0 mL of 0.100 M ethylamine (CH3CH2NH2) with 0.05 M HCl. Kb for ethylamine = 6.4x10-4 1. Identify the analyte and the titrant.

2. How many mL of HCl must be added to reach equiv pt? 3. Calc initial pH. 4. Calc pH if add 5.00 mL of HCl. 5. Calc pH at equiv pt. 6. Calc pH if add 60.0 mL of HCl. Solubility Equilibria

Looks at equil between (s) and ions (salts dissolved in water at saturation point) Ex. NaCl (s) Na+ (aq) + Cl- (aq) When put salt in water, it dissolves. As ions build up, they can reform the salt. At some point, establish eq = saturation point.

Since we have equil, we can write a K expression. Ksp (solubility product constant) Ksp = [Na+][Cl-] Ksp Ksp tells about how soluble or not a salt is-explain

Solubility is the same as [ ] so for NaCl, NaCl (s) Na+ (aq) + Cl- (aq) if 1 M, then if S, then Ksp= [Na+][Cl-] = (S)(S) = S2 Solubility, S = Ksp = M units

1. If AgBr (s) has Ksp = 1.6x10-10 at 25oC, what is solubility in M? 2. What does that # mean in words? Write Ksp expression for magnesium bromide (s) dissolving in water in terms of [ ] and S.

Calculate Ksp if, at 25oC, S = 0.0159 M. Which is more soluble AgCl or NiS? Ksp AgCl = 1.6x10-10 Ksp NiS = 3x10-21 Which is more soluble AgCl or Ba(OH)2?

Ksp AgCl = 1.6x10-10 Ksp Ba(OH)2 = 5x10-3 Common Ion Effect? Calc S of CaF2 (Ksp = 4x10-11). Will S be affected if add NaF? Explain. Calc S of CaF2 in a solution of 0.025 M NaF.

Does pH affect solubility? Ba(OH)2 (s) Ba2+ (aq) + 2 OH- (aq) If add HCl (pH), would solubility change? What about adding NaOH?

Consider NaNO2 (s) Na+ (aq) + NO2- (aq) If add HCl would solubility change?

Would MgBr2 be more soluble in acid or water? Will ppt form? Compare Qsp to Ksp If Qsp > Ksp, ppt will form If Qsp < Ksp, no ppt Will ppt form when 100. mL of 4x10-4 M Mg(NO3)2 is mixed with 100. mL of 2x10-4 M NaOH? Ksp Mg(OH)2 = 1.8x10-11