Question

13. Calculating the composition of a buffer of a given pH. a) Kb=5.4*10-4 125mL of 0.90M (CH3)2NH Calculate the mass of (CH3)2NH2Br should the student dissolve in the (CH3)2NH solution to turn into a buffer with pH=10.70. MW-125.9956g/mol b) Ka=4.5*10-4 125mL of 1.40M HNO2 solution Calculate the mass of KNO2 should the student dissolve in the HNO2 solution to turn into a buffer with pH=3.30

Answer 1

ky- 5.4 8109 pth = -los (5 4X10%) = 3.2676 no . q moles y cate)r n = 125 2x o-rounde 1000 = 0.1125 set x be the no.rules of (af alt, Br pH = 10.70 pot - 14- 10.20 3.3 Apply Hendersons aquation pot = pks + log [(CH 2 WH, B) [(CH NH) 3.3 = 3.2676 + loa remot to 125mil) 1032 ) = 3.3-3.2676 100.0324 = 1.077457 0.1125 10.125 ) 2 = 0.1212139 no. of molez (atz 4 B8 = 0.1212139 mile Mapp q (014), 0004_B7 = 0.12127.89 rubl 125.99563 - 15.2727 215.32 ) 15 g /

в по ме - чао у 11 404 onsult <at 04 пове кос, — ра: -20 4.5 x 16) 3. 3 6 7 5 - о. 65 3) = ре - rka 4 goy CHNO 1 3. 30 : 3.34 67 + goal zuke 10.175 more) 90 ) ( ) - 2 - 30 - 3. 3467 б. Ode62 o: 175 х = 0. 370 41 у с. 125 = c. 15715 по 7 42koo : о. 15715 4 на и сир кор 235.103 77 Э. Magg + kog = о 15 15 & x65. to s2 3 але 13. 373 с 13. 3