Work Session 19 Ionic Equilibria 1 Explain why sodium acetate and acetic acid together in solution make a buffered solution but sodium chloride and hydrochloric acid do not make a buffered solution when mixed 2 Write the appropriate other component for the following substances to make a buffered system Write the other component below the printed one If one of the components is shown as an ionic compound with a cation or anion attached rewrite the substance as the ion that is the actual component of the buffer HIO NaCN C5H5NH HF NH4Cl KNO2 3 What would you use to get a buffer system with a pH of around 4 2 What would you use to make a buffer with a pH of around 9 2 Describe the process you used 4 A buffer is made by mixing NH4Cl and NH3 Which is the acid component and which is the base component What is the Ka for the NH4 ion calculate from the Kb of its conjugate base 5 A buffer is made by mixing 0 30 moles of propanoic acid HC3H5O2 and 0 20 moles of sodium propanoate Na C3H5O2 What will the pH of the solution be Note that the formulas are shown in condensed form here Ka for propanoic acid is 1 3 x 10 5 6 For the mix in question 5 show the reaction that takes place when a strong acid is added to the solution Show the reaction that takes place when a strong base is added to the solution 7 When a strong acid is added to a buffer solution does the pH of the buffer go up or down Use the Henderson Hasselbalch equation to explain why this is so Also use this to explain what happens when a strong base is added to the buffer 1 Name Grade Date 8 Finish and balance the following HCl NaOH HC2H3O2 NaOH NH3 HCl Show each of the ionic products written out as individual ions Indicate whether the ions would be acidic neutral or basic 9 The reactions in number 8 are for a strong acid strong base weak acid strong base and weak base strong acid respectively The reactions shown with equal moles of each substance reacting occur at the equivalence point Generalize about the pH at the equivalence point for these three types of titrations 10 20 ml of 0 100 M weak acid is titrated with a 0 100 M NaOH solution Here is data showing the pH as various quantities of base are added ml 0 ml 10 ml 20 ml 25 ml pH 2 37 3 74 8 22 12 05 What is the Ka of the acid Which of the above points is the equivalence point 11 Silver sulfate Ag2SO4 dissolves to the extent of 4 84 grams per liter What is the Ksp of silver sulfate from this data 12 Which of the following slightly soluble substances are more soluble in acidic solution AgCl Explain why 13 50 0 ml of a solution containing 0 010M Pb NO3 2 is mixed with 50 0 ml of a solution containing 0 10 M NaCl What will the concentrations of Pb and of Cl be after the mixing PbCl2 has a Ksp 1 7 x 10 5 What is the value of Q for the lead and chloride ions Will a precipitate form in the mixture Why or why not 14 The Ksp for PbI2 7 9 x 10 9 What is the solubility of lead iodide in water What is the solubility of lead iodide in a 0 10 M NaI solution 2 AgCN CaF2