Check for Understanding Acid Base & Polyprotic Acids

Check for Understanding 1. The K b of ethylamine C 2 H 5 NH 2 , is 6.4 x 10 -4 . Calculate the pH, pOH, [OH - ], [H 3 O + ] of a 0.075 M solution of ethylamine. 2. Calculate the pH of a 0.237 M solution of benzoic acid, C 6 H 5 COOH (K a = 6.14 x 10 -5 ). What is its % ionization? Acid Base for Polyprotic Acids Many acids have more than one ionizable H atom. These acids are known as Polyprotic acids. H 2 SO 3 + H 2 O ó H 3 O + + HSO 3 - K a1 = 1.7 x 10 -2 HSO 3 - + H 2 O ó H 3 O + + SO 3 2- K a2 = 6.4 x 10 -8 Note:  K a1 vs K a2  Difference between K values 1. What is meant by the symbol K a3 for Phosphoric acid? Write the dissociation reaction for each hydrogen. 2. What is the pH of a 0.0037 M solution of H 2 CO 3 ? K a1 = 4.3 x 10 -7 K a2 = 5.6 x 10 -11