144 13- 12. 11 Titration of Weak Acid 10- 9 86 7. Equivalence point pH, 8.72 65 A 4 3- 210 0001-0 to nojuan anta 0 5 10 15 20 25 30 35 40 45 50 Volume of 0.100 M NaOH added (mL) Fig. 10.2: Titration curve of a weak acid with a strong base The shape of a titration curve depends on the ionization constants of the acid and base and their concentrations. The example given above is for a weak acid and strong base. The equivalence point is defined as the point where the amount of base added is equal to the original amount of acid in the solution. Therefore, at the equivalence point, the number of moles of base added equals the number of moles of acid originally present in the solution being titrated. After determining the equivalence point, the concentration of the basic solution can be easily calculated with the titration formula (when the stoichiometry of acid and base is 1:1): Molarity of acid (mol/L) x Volume of acid = Molarity of base (mol/L) x Volume of base Macid X Vacid = Mbase X Vbase moles of acid in original solution = moles of base added Concentration of base (mol/L) or [base] = [moles of acid in original solution] (volume in L of base at equivalence point)

144 13- 12. 11 Titration of Weak Acid 10- 9 86 7. Equivalence point pH, 8.72 65 A 4 3- 210 0001-0 to nojuan anta 0 5 10 15 20 25 30 35 40 45 50 Volume of 0.100 M NaOH added (mL) Fig. 10.2: Titration curve of a weak acid with a strong base The shape of a titration curve depends on the ionization constants of the acid and base and their concentrations. The example given above is for a weak acid and strong base. The equivalence point is defined as the point where the amount of base added is equal to the original amount of acid in the solution. Therefore, at the equivalence point, the number of moles of base added equals the number of moles of acid originally present in the solution being titrated. After determining the equivalence point, the concentration of the basic solution can be easily calculated with the titration formula (when the stoichiometry of acid and base is 1:1): Molarity of acid (mol/L) x Volume of acid = Molarity of base (mol/L) x Volume of base Macid X Vacid = Mbase X Vbase moles of acid in original solution = moles of base added Concentration of base (mol/L) or [base] = [moles of acid in original solution] (volume in L of base at equivalence point)

Chemistry: An Atoms First Approach

2nd Edition

ISBN:9781305079243

Author:Steven S. Zumdahl, Susan A. Zumdahl

Publisher:Steven S. Zumdahl, Susan A. Zumdahl

Chapter14: Acid- Base Equilibria

Section: Chapter Questions

Problem 118CP: Malonic acid (HO2CCH2CO2H) is a diprotic acid. In the titration of malonic acid w ith NaOH,...

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Malonic acid (HO2CCH2CO2H) is a diprotic acid. In the titration of malonic acid w ith NaOH, stoichiometric points occur at pH = 3.9 and 8.8. A 25.00-mL sample of malonic acid of unknown concentration is titrated with 0.0984 M NaOH, requiring 31.50 mL of the NaOH solution to reach the phenolphthalein end point. Calculate the concentration of the initial malonic acid solution. (Sec Exercise 113.)
Given three acid-base indicatorsâ€”methyl orange (end point at pH 4), bromthymol blue (end point at pH 7), and phenolphthalein (end point at pH 9)â€”which would you select for the following acid-base titrations? (a) perchloric acid with an aqueous solution of ammonia (b) nitrous acid with lithium hydroxide (c) hydrobromic acid with strontium hydroxide (d) sodium fluoride with nitric acid
When 40.00 mL of a weak monoprotic acid solution is titrated with 0.100-M NaOH, the equivalence point is reached when 35.00 mL base has been added. After 20.00 mL NaOH solution has been added, the titration mixture has a pH of 5.75. Calculate the ionization constant of the acid.
In an acid-base titration, 21.16 mL of an NaOH solution are needed to neutralize 20.04 mL of a 0.0997 M HCl solution. To find the molarity of the NaOH solution, we can use the following procedure: First note the value of MH in the HCl solution. ____________M Find MOH- in the NaOH solution. Use Eq.3. ____________M Obtain MNaOH from MOH. ____________M
A 0.400-M solution of ammonia was titrated with hydrochloric acid to the equivalence point, where the total volume was 1.50 times the original volume. At what pH does the equivalence point occur?