Question

SUPPLEMENTAL PROBLEM: Consider the titration of 25.00 ml. of 0.180 M AsO with 0.150 M HCL Ka, for HsAsO-6x 10 K for HsAsO-1.1 x 10 Ka, for HsAsO-3 x 10 a) How many milliliters of HCI are needed to reach the 1". 2, and 3 cquivalence points in this titration? b) What is the pH of the 0.180 M AsO solution before any HCI is added c) What conjugate pair is present at the first midpoint? d) Determine the approximate pH at the first midpoint. e) What conjugate pair is present at the second midpoint? Determine the approximate pH at the second midpoint. g) Estimate the pH at equivalence point # . h) What conjugate pair is present at the third midpoint? Determine the approximate pH at the third midpoint. i) Estimate the pH at equivalence point #2 k) Sketch the titration curve using the calculated volumes and your estimated pl values. Label the axis. Label midpoints 1-3 and equivalence points 1-3 with the titrant volumes and their corresponding pH values.

Answer 1

1s! eaulaience potah - 2 HASO moles Asaz moles Ht added O-8om 25 00mL B0-OML So eavvalence pon Converted o As 2x 30-0mL 600ml 2 Ve 3d equlvalenie point Asa3 t 3HT HASQ HT 2 60-omL+30-om volume e auivalence HO-oml bekore only base let t A-3 Atmo HAZ oH O-180 m G -180-x kas kw 2 calculate to33x 3x 10 Icas 1 3.3 x(03 CMA CON CAS 2 2 3-3x103 2 O-180-x 3.3x163 t .000054 20 auadrat eavarn Solver Use 2 COM)1 -109 Co006) 2-2 p on 2. 2 1-8 2 14-2-2

md Point A3 har Conver hed ns of So Condugate base Acld pH 2 pkas So C8 CA as hend eavah CAD 2 0g C3 10 mid poinh Second halr df Heve MA Fovmed eautvalence pot Conveve d to H Condugat 2 (HA base ACId pIcaz 2 1s H,A CA S acid 1ay Kar 2 1C-1x10 C-96 9 equive ence point he Speces present HAL (wnh ns ampholee ba se 1s acts pkar p cas So 11-5+6-9G 19-23 hak of fovned at second equclence pont Convev te d 15 My A So base 15 AA actd condugate Palr A/HA pica T -10g Cax163) 2 2-2

eauivalence point Spec es A Camphokenc) present s 1-e pH pkai tpkaL 2-2 t 6-96 4.58 6 volume of acd Cn mi pH 11-5 stmd ponfAs) CHAs ppas 923 3 equvalence pon 2 d pol 6-96 2nd eaulvatence pont Y-6 2 mid poin 2-2 3 equlvalene point 30ML 60 mL af as ld In m volume p 2.2 For 2 equivatence point Shralght dvaw do wn 3vd mid pank coveck p