Question 8: Fill in the mass values to 2 significant figures Calculate the mass in grams of sodium nitrite (NaNO2) that must be added to 500.0 mL of 0.020 M nitrous acid (HNO2) to make a pH 4.00 buffer. Neglect volume changes. Calculate the mass in grams of ammonium bromide (NH4Br) that must be added to 500.0 mL of 0.030 M ammonia (NH3) to maks a pH 9.00 buffer. Neglect volume changes.

Question 8: Fill in the mass values to 2 significant figures Calculate the mass in grams of sodium nitrite (NaNO2) that must be added to 500.0 mL of 0.020 M nitrous acid (HNO2) to make a pH 4.00 buffer. Neglect volume changes. Calculate the mass in grams of ammonium bromide (NH4Br) that must be added to 500.0 mL of 0.030 M ammonia (NH3) to maks a pH 9.00 buffer. Neglect volume changes.

Chemistry: Principles and Reactions

8th Edition

ISBN:9781305079373

Author:William L. Masterton, Cecile N. Hurley

Publisher:William L. Masterton, Cecile N. Hurley

Chapter14: Equilibria In Acid-base Solutions

Section: Chapter Questions

Problem 25QAP: A sodium hydrogen carbonate-sodium carbonate buffer is to be prepared with a pH of 9.40. (a) What...

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Enough water is added to the buffer in Question 29 to make the total volume 10.0 L. Calculate (a) the pH of the buffer. (b) the pH of the buffer after the addition of 0.0500 mol of HCl to 0.600 L of diluted buffer. (c) the pH of the buffer after the addition of 0.0500 mol of NaOH to 0.600 L of diluted buffer. (d) Compare your answers to Question 29(a)-(c) with your answers to (a)-(c) in this problem. (e) Comment on the effect of dilution on the pH of a buffer and on its buffer capacity.
Briefly describe how a buffer solution can control the pH of a solution when strong acid is added and when strong base is added. Use NH3/NH4Cl as an example of a buffer and HCl and NaOH as the strong acid and strong base.
Consider all acid-base indicators discussed in this chapter. Which of these indicators would be suitable for the titration of each of these? (a) NaOH with HClO4 (b) acetic acid with KOH (c) NH3 solution with HBr (d) KOH with HNO3 Explain your choices.
A solution made up of 1.0 M NH3 and 0.50 M (NH4)2SO4 has a pH of 9.26. a Write the net ionic equation that represents the reaction of this solution with a strong acid. b Write the net ionic equation that represents the reaction of this solution with a strong base. c To 100. mL of this solution, 10.0 mL of 1.00 M HCl is added. How many moles of NH3 and NH4+ are present in the reaction system before and after the addition of the HCl? What is the pH of the resulting solution? d Why did the pH change only slightly upon the addition of HCl?
What is an acidbase indicator? Define the equivalence (stoichiometric) point and the end point of a titration. Why should you choose an indicator so that the two points coincide? Do the pH values of the two points have to be within 0.01 pH unit of each other? Explain.
Ka for formic acid is 1.7 104 at 25C. A buffer is made by mixing 529 mL of 0.465 M formic acid, HCHO2, and 494 mL of 0.524 M sodium formate, NaCHO2. Calculate the pH of this solution at 25C after 110 mL of 0.152 M HCl has been added to this buffer.
Calculate the mass of sodium acetate, NaCH3COO, you should add to 500. mL of a 0.150-M solution of acetic acid, CH3COOH, to buffer a solution at a pH of 4.57.
Given the acid-base indicators in Question 37, select a suitable indicator for the following titrations. (a) sodium formate (NaCHO2) with HNO3 (b) hypochlorous acid with barium hydroxide (c) nitric acid with HI (d) hydrochloric acid with ammonia
Enough water is added to the buffer in Question 30 to make the total volume 5.00 L. (a) Calculate the pH of the buffer. (b) Calculate the pH of the buffer after adding 0.0250 mol of HCl to 0.376 L of the buffer. (c) Calculate the pH of the buffer after adding 0.0250 mol of KOH to 0.376 L of the buffer. (d) Compare your answers to Question 30 (a-c) with your answers to (a-c) of this problem. (e) Comment on the effect of dilution on the pH of a buffer and on its buffer capacity. Â
Identify the buffer system(s)the conjugate acidbase pair(s)present in a solution that contains equal molar amounts of the following: a. HF, KC2H3O2, NaC2H3O2, and NaF b. HNO3, NaOH, H3PO4, and NaH2PO4
Sodium benzoate, NaC7H5O2, is used as a preservative in foods. Consider a 50.0-mL sample of 0.250 M NaC7H5O2 being titrated by 0.200 M HBr. Calculate the pH of the solution: a when no HBr has been added; b after the addition of 50.0 mL of the HBr solution; c at the equivalence point; d after the addition of 75.00 mL of the HBr solution. The Kb value for the benzoate ion is 1.6 1010.
Identify each pair that could form a buffer. (a) NaOH and NaCl (b) NaOH and NH3 (c) Na3PO4 and Na2HPO4