Question

Propanoic acid (abbreviated as HPro K, - 13 x 10) is produced naturally by a bacterium that is also responsible for forming the holes in Swiss cheese. An extract of 45.0 mL of HPro from some cheese had a propanoic acid molarity of 0.0150 M. This was titrated with 19.85 mL of 0.034 M NaOH. What was the pH of the resulting solution? OA 9.11 OB 7.02 Oc555 OER

Answer 1

Date Page CH3-CH2COOH + NaOH CH3 CH2COonat H2o millimole's ok CH3-CH2-Coop = 45.omly 0:01 OM = 0.61 millimole's ok NagH I 19.858 0.034 = 0.6749 ✓ 0.675 millimole's ok chahH2 coon = millimoles of Naoh find pH at equi- .. we have to - valence point CH₃-CH2-woh + Nuor millimores Lly 0.675 0.675__ (Hg CH₂ coona+H2O (salt) 0.675 I Thus is 0. 675 millimoles of CH3 CH2Coona formed.( Total volume =45+19.85) = 64.85

Date Page CH3 CH2 cooNa] = mittimoles of salt Totcel volume - 0.675 64.85 - 0.0104086 / undergues dissociate CH3CH2coona as follow's CH3CH2COona + H20 - CH3CH2COOH + OH Initiw -0.0104086 0 0 at equilibrium 0.0104086-2 * Calculate knc hydrolysis constant). СсHz CH, сооңу[оң) Lх = ICH3 CH2-2003 -oot04086 - - - .kn I 0.0104086-n 0.0104086 22. Cu En - Orolones

Date Page Kw - dissocicetion -Kwa Kha- content ok touter kw=1x10 -5 Kaz 1.3 X lo X10-14 Kn=- t. 3810-S kn=7.6923 810 www -2) kn = I from (1) anti 0.0104086 (2) 7.6923 - x² o.olouo86 7.6923X10 Xо.0104086 m² L2 8.006 x 10 = ² 2.82 810 6 = x T Taking square 106 root

Date Page, Сон-Тех - 2.82x10-6 С 2 рби - - Поз Сон - - Те: L2 - 82xio - J реи : 5:549] 50 -4) ри + PoЯ - 14 ри+ 5-S14+50 - 14 ри: 14 - 5:549+so РИ - 8. 4s o25 ри - 8.45 L PH os solution is 8.45 option is correct E- 8.45

Correct answer E. 8.45.

Solution of given question have several part's,

First calculate millimoles of acid and base,

Then concentration of salt formed

Then value of Kh( hydrolysis constant)

by the value of Kh find out value of concentration of salt.

Finally find out pOH, with the help of pOH find out pH.