4. You need to make a buffer with pH as close to 10.00 as possible. Two sets of weak acids and conjugate bases, with the Ka values, are listed below. Which of the two sets would be the best choice? You want a pKa close to the pH. Explain your reasoning. CH3COOH/CH3COO HCO3 /CO;? Ka = 1.80 x 105 Ka = 2.14 x 10-10

A buffer contains 0.175 moles C2H5NH3NO3 and 0.225 moles C2H5NH2 in 800.0 mL water. Kb (C2H5NH2) = 4.3 x 10-4   Express value to three decimal places.   Determine the number of moles of acid that can be added before the buffer capacity is exceeded.

Phosphoric acid is a triprotic acid (Kal = 6.9 x 10-3, K22 = 6.2 x 10-8, and Ka3 = 4.8 x 10-13). To find the pH of a buffer composed of H, PO, (aq) and HPO? (aq), which pK, value should be used in the Henderson-Hasselbalch equation? pKal = 2.16 O pKa2 = 7.21 O pKa3 = 12.32 Calculate the pH of a buffer solution obtained by dissolving 18.0 g of KH, PO,(s) and 37.0 g of Na, HPO,(s) in water and then 4. diluting to 1.00 L. pH =

1.What is the Ka of a weak acid, HA, that forms a buffer of pH 5.50 when combined in an equal concentration with its conjugate base, A−? Answer: Ka= ...... x 10^-6 2.Calculate the pH of 0.136 M potassium nitrite, KNO2. The ionization constant of nitrous acid, HNO2, is Ka= 5.6× 10-4   3.Calculate the pH of a solution of magnesium hydroxide, Mg(OH)2 (Ksp = 5.6 × 10−12), made by dissolving solid Mg(OH)2 in pure water until the solution is saturated.