Question

Consider the titration of 100.0 mL of the weak diprotic acid H2A (0.10 M) with 0.20 M NaOH. What are the major species at each of the following points in the titration? (Water is always assumed to be a major species.)

1. Before any NaOH is added

2. After 25.0 mL of 0.20 M NaOH is added

3. After 50.0 mL of 0.20 M NaOH is added

4. After 75.0 mL of 0.20 M NaOH is added

5. After 200.0 mL of 0.20 M NaOH is added

Answer 1

1. Before any NaOH is added - H2A

2. After 25.0 mL of 0.20 M NaOH is added - H2A

3. After 50.0 mL of 0.20 M NaOH is added - H2A

4. After 75.0 mL of 0.20 M NaOH is added - H2A

5. After 200.0 mL of 0.20 M NaOH is added - NaOH

Answer 2

vaoh added Answer 1) Before any Tales of 4A= = Colority & Volume 0.1 x 100 x 10-3 0.01 roles. ka i HAO + hot t no HA Exams 0.01 0.01 Initially d.ol After co A2 + 1 hot HAD +ho lazan Initially o.al 0.014 0.01 0.01 A² 0.ol moles i constituents 0.02 moles. so, major 2) After 25.0mL of 0.211 Noon is added moles of Naon = 0.2 x 25.0*10-3 = 0.005 IHA tono ka HAS +40 Tistically. 0.01 0.005 After o.ol-0.005 o 0.005 Excurs +0.005 o exam

anitially 0.005 moles o 0.005 o 0.005 x H 5x10 moks rajor constituents after 2 - 5x lo moles Hot - 5-10 mokes 3 After 50.0 mL of 0.20 M Naon added roles of Naon = 0.2 x 50 x103 = 0.01 moles liga top HA 40 0.01 Orol o excess dool 0.01 + Exces Initially After nich Initially 0.01 0.01 Dool 0 o ol moles al moles Mayor Corstituents after r":

4 After 75.0 mL of 0.29 Naon es cedded moles of Naon = 0.2x75x10-3 = 0.015 rooles 07. 11 நயர் FIA HA tono 2nd Initially After si dool 0.015 o 0.015-0.01 A to HAS Intestly o.ol tou 5x10-3 Excus 5x103 Eurs 5x103 5x10 modes After 0.0/- 5x120 HAD ४ाट A2 - 5x10? moles Mujor consteluents after or 5 for 200.0mL d 0.200 ohon added Hobs of Noon 0.2 200 102 = 0.0 y moles o escas 0.01 Excess D-02 males 0.04 0.04-0.ol. Instintly o.ol Aflar o or Constituents - Hash A 2 d. al moles o Excess Dool imees artidly o.ol 0.03 Alno o 0.03-0.01