patino_chm2046_chapter16

Equilibrium calculation 2 equilibrium calculation

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Unformatted text preview: inal solution? What Strategy — ffind the conc. of the Strategy — ind the conc. of the conjugate base, Bz−,, iin the solution @ conjugate base, Bz− n the solution @ tthe END of the titration, then calculate he END of the titration, then calculate pH. pH. This is a two-step problem This is a two-step problem 1. stoichiometry off acid-base 1. stoichiometry o acid-base reaction reaction 2. equilibrium calculation 2. equilibrium calculation Acid­Base Reactions Acid­Base Reactions Q:Titrate 100. mL of a 0.025 M solution of benzoic acid with Titrate 0.100 M NaOH to the equivalence point. What is the pH of the final solution? the STOICHIOMETR Y PORTION STOICHIOMETR Y PORTION 1. Calc. moles of NaOH req’d 1. Calc. moles of NaOH req’d (0.100 L HBz)(0.025 M) = 0.0025 mol HBz (0.100 L HBz)(0.025 M) = 0.0025 mol HBz This requires 0.0025 mol NaOH This requires 0.0025 mol NaOH This 0.0025 This 0.0025 2. Calc. volume of NaOH req’d 2. Calc. volume of NaOH req’d 0.0025 mol (1 L // 0.100 mol) = 0.025 L 0.0025 mol (1 L 0.100 mol) = 0.025 L 25 mL of NaOH req’d 25 mL of NaOH req’d Or, from Mac Vac = Mbase Vbase Or, from Mac Vac = Mbase Vbase Or, Or, base base we get Vbase = 25 mL we get Vbase = 25 mL Acid­Base Reactions Acid­Base Reactions Q: Titrate 100. mL of a 0.025 M solution of benzoic acid with 0.100 M NaOH to the equivalence point. What is the pH of the final solution? final STOICHIOMETRY PORTION STOICHIOMETRY PORTION HBz + OH− → Bz− + H2O K is too large. HBz + OH− → Bz− + H2O K is too large. HBz HBz 25 mL of NaOH req’d 25 mL of NaOH req’d 25 25 3.. Moles of Bz-- produced = moles HBz = 0.0025 mol 3. Moles of Bz produced = moles HBz = 0.0025 mol 3. 0.0025 3 0.0025 4. Calc. conc. of Bz-4. Calc. conc. of Bz There are 0.0025 mol of Bz-- iin a TOTAL There are 0.0025 mol of Bz n a TOTAL SOLUTION VOLUME of 125 mL = (100. + 25). mL SOLUTION VOLUME of 125 mL = (100. + 25). mL SOLUTION SOLUTION [Bz-] = 0.0025 mol / 0.125 L = 0.020 M 0.0025 0.020 Ac id ­Ba s e R e a c tio ns Ac Q: Titrate 100. mL of a 0.025 M solution of benzoic acid with 0.100 M NaOH to the equivalence point. What is the p...
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