3) 2.413 g sample contains Na CO̟, NaHCO and inert material. This sample was solved in water and diluted to 250.0 ml. 80 ml solution was taken and titrated with 0.09644 N HCl with the indicator of phenolftalein. 6.13 ml HCl was consumed. From a second solution, again 80 ml was taken and titrated with the same HCl solution with the indicator of methylorange. 15.4 ml HCl was consumed. Calculate the percentage of NaHCO¸ and 3 Na CO in sample (Na CO_=106.0 g/mol, NaHCO_=84.02 g/mol). 3

3) 2.413 g sample contains Na CO̟, NaHCO and inert material. This sample was solved in water and diluted to 250.0 ml. 80 ml solution was taken and titrated with 0.09644 N HCl with the indicator of phenolftalein. 6.13 ml HCl was consumed. From a second solution, again 80 ml was taken and titrated with the same HCl solution with the indicator of methylorange. 15.4 ml HCl was consumed. Calculate the percentage of NaHCO¸ and 3 Na CO in sample (Na CO_=106.0 g/mol, NaHCO_=84.02 g/mol). 3

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter15: Acid-base Equilibria

Section: Chapter Questions

Problem 132IP: A 10.00-g sample of the ionic compound NaA, where A is the anion of a weak acid, was dissolved in...

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A 10.00-g sample of the ionic compound NaA, where A is the anion of a weak acid, was dissolved in enough water to make 100.0 mL of solution and was then titrated with 0.100 M HCl. After 500.0 mL HCl was added, the pH was 5.00. The experimenter found that 1.00 L of 0.100 M HCl was required to reach the stoichiometric point of the titration. a. What is the molar mass of NaA? b. Calculate the pH of the solution at the stoichiometric point of the titration.
A buffer is prepared by dissolving 0.062 mol of sodium fluoride in 127 mL of 0.0399 M hydrofluoric acid. Assume no volume change after NaF is added. Calculate the pH of this buffer.
A bottle of concentrated hydroiodic acid is 57% HI by weight and has a density of 1.70 g/mL. A solution of this strong and corrosive acid is made by adding exactly 10.0 mL to some water and diluting to 250.0 mL. If the information on the label is correct, what volume of 0.988 M NaOH is needed to neutralize the HI solution? Suggest an indicator for the titration.
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.
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.)
The titration of 0.100 M acetic acid with 0.100 M NaOH is described in the text. What is the pH of the solution when 35.0 mL of the base has been added to 100.0 mL of 0.100 M acetic acid?
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
50 mL sample solution containing Na2CO3 and NaOH is titrated with 0.2 M HCl solution. In the presence of phenolphthalein indicator, the acid consumption is 15 mL. Then, the titration is continued by adding bromocresol green indicator, and in the presence of this indicator, the acid consumption is 10 mL. Accordingly, which of the following is the amount of Na2CO3 (in grams) in the sample? (NaOH: 40 g / mol; NazCO3: 106 g / mol)
A titration curve is constructed by plotting the pH of the analyte solution versus the volume ofthe reagent added as the titration progresses. As the equivalence point is approached, there is arapid change in the pH. Titration curves enable us to explain how end points are detected andtheir relationship to equivalence points. They can also serve as guides for choosing the properindicators for a particular acid-base titration. Explain how each plot can be used to interpret the acid-base titration.
An approximately 0.1-molar solution of NaOH is to be standardized by titration. Assume that the following materials are available. Clean, dry 50 mL buret •Analytical balance 250 mL Erlenmeyer flask •Wash bottle filled with distilled water Phenolphthalein indicator solution Potassium hydrogen phthalate, KHP, a solid monoprotic acid (to be used as the primary standard) Briefly describe the steps you would take, using the materials listed above, to standardize the NaOH solution. Describe (the set up) the calculations necessary to determine the concentration of the NaOH solution.
A 1.2 g sample of mixture of NaOH and Na:COs containing inert impurities s dissolved and titrated cold with 0.5N HCI. With phenolphthalein as indicator the solution turns colorless after the addition of 30.0 mL of the acid. Methyl orange is then added and 12 ml more of the acid is required before this indicator changes color. What is the percentage of NaOH and of Na:COs in the sample ?
What is the solution to this problem? Given answer is 24.51% NaOH ; 64.95%Na2CO3