Chapter 15, Problem 56P

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?

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

Write the chemical equation and the expression for the equilibrium constant, and calculate Kb for the reaction of each of the following ions as a base. (a) sulfate ion (b) citrate ion

Does the pH of the solution increase, decrease, or stay the same when you (a) Add solid sodium oxalate, Na2C2O4, to 50.0 mL of 0.015-M oxalic acid? (b) Add solid ammonium chloride to 100. mL of 0.016-M HCl? (c) Add 20.0 g NaCl to 1.0 L of 0.012-M sodium acetate, NaCH3COO?

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.

The pigment cyanidin aglycone is one of the anthocyanin molecules that gives red cabbage (Brassica oleracea var. capitata f. rubra) its characteristic red coloration. Many chemistry students have used this red cabbage indicator to study acid-base chemistry. Estimate tire pH range at which cyanidin agly-cone shows a color change. Anth-H(aq) Anth(aq) + H+ (aq) Ka = 1.3 107

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.

. A buffered solution is prepared containing acetic acid, HC2H3O2, and sodium acetate, NaC2H3O2, both at 0.5 M. Write a chemical equation showing how this buffered solution would resist a decrease in its pH if a few drops of aqueous strong acid HCI solution were added to it. Write a chemical equation showing how this buffered solution would resist an increase in its pH if a few drops of aqueous strong base NaOH solution were added to it.

A student titrated 30.00 mL of a weak base solution, 0.150 M CH₃NH₂ (Kb = 4.40 × 10⁻⁴), with 0.100 M HCl solution. Calculate the pH at the equivalence point.