Question

3) (10 points total) A 25.0-mL sample of 0.35 M HCOOH (formic acid) is titrated with 0.20 M KOH. What is the pH of the solution after 25.0 mL of KOH has been added to the acid? Ka-1.77 x 10 a) (4 points) What is the pH of the solution after 25.0 mL of KOH has been added to the acid? Ks-1.77 x 10 C 2-l04Co1s5 b) (6 points) Calculate at least nine (9) more titration points, build a table and draw out the titration curve for formic acid with KOH. Be detailed in the plot and correctly label the equivalence point, half equivalence point and the axes.

Answer 1

moles HCOOH moles (colt - 2 - 2 a - 0.35m x 25.ome 8.75 mmoles 0-20m x 250 ml s 0 mmole 2 - کے Hcool & Koll Hooo- kt the 8.25 S-o o -50 +5-0 3.75 Sowtren as buffer as weak cold HCOOH and conusare bar Heae pleca a tog (ka) 2 tog (1-77x154) present 2 3.752 pH a pica & log ( 3 ) 23-75.2 + log (sommes un 3-25 mmden ut 2 3-877. z 3.88

4600 titt nu pH t HCOOH 0:35 cx соу-х neglect x) use - Lov) Kar Cacoo Curt) THCoon) 1-77x104 ax 035- quadrane equatta solver x2 + 1.778104x - 0.00006195 20 x 2 0 .0078 M Cut) pr 2.11) and powry 5mL KOH moles Hooo 2 0 20m x Toml = mdes koh 40 mmoly a 8.75 mmoles - 1.0 2 7.75 mmoles moles Hoooh Cleft 2 plz 3-752 + log. lo mmoles 7-75 mmoles 22.86 3rd pointy Lome 100H (calculate same as abure yin powl? 12.5 mL lcat. Calculate equivalence point t o moles Heoch a mdes koh 8-75 mmoles (KOH) 0-20 m 2 43-25 mL = 44ml har -eanualence point & ve 21.885 mL = 22ml

at half - equivalence point (acoor CA Cncool 2 (B) so pH a pica 3-752. on point 2500 ml en point 200 ml moles moles base, 4coo z o-200x 3o-ome = 6 mmole HCOOH ciert 2 8.75 -6.0. - 2.75 mmoll pa 3-752 + logg M.09 8th point 35-0 ml calcolate same as above gh point equna lence point all Hcoon converted to Hoo Cacts as have CHCor 2 moles ecoar antial Total volume 8.25 mmoles 25.0mL +43-75ML 0-13 m. calculate 16 z ko 2 l-oox toy 1-778164 25.65 x 10l! Hoo + H2O 2 HOOOH tot e 0.13 (neglect & ask is very less) & CHCOOH Con Cucos 5-65*10" = 5 * 2 Con22.98 tom S.57 2 PH 14.00 -9.522 18:43] 2) por

rough core & exces 011 Catralence 243) Point (PMI) pH pka hat - Claulvalence pent 20 22 m OMC volume TEOH (nm)