Question

caculate the ph during the titration of 20.0mL of 0.10M H2C2O4 with 0.10M NaOH after the addition of the following volumes of NaOH reagent: A. 20.0mL B.30.0mL C.Suggest an indicator that could be used to provide an end point for the titration of the second proton(H+) in H2C2O4 described above. (H2C2O4: K1=5.6 × 10'-2 K2=5.4 × 10'-5)

Answer 1

oxalic aciel anal Na OH Neutralization Aeaction COONA COOH + 2H20 +2 NaoH CooH COONO et neutrali 2ed 70xalic acid Imole NaoH 2 moles of 20 mL O xalic acid in Number o moles O.10 X20 =0.002 moles O.1oM Molution 1000 O.1ON Numbes fmoles NaoH in 2.0 mL O.to x2o olution =0.002 moles 1000 to tha O xal'c Adter addition aud solution NaoH 90mL O xalic acid 0.001 moles emly will neat accos ding to balauced eaction mo acid oiI emain in the O.ool moles slution Aolution is due So acid. Thus s comcentiation Hhese oxalic pH=-A0g = -log Co.0017 -og Lx137 CH+ IX adl dition 30 mL NaoH to Apter O.001 moles 7 As Molution Bndy solution t hese Hhe i'spresent au'd the 0.002 m0oles with base will peact

sill nemaiu unneutializeal Rest base NaoH in 30mL Namber o moles of O10 3o O.003 moles l000 NaoH Laft Moles O003-o.002 O.001 moles O.00l moles These Naoh Concentration pOH = -d0g EoH 3 paH pon 14 pH E 14-3 Cc) Phenophthein used indicator i's an as neutrali zation eactrons in for he NaoH s ued base wlich as colonlors in acidic meolium is It changes Lght pink Cud t0 baric me dium in