Can you also explain how you know when you use before reaction and after reactio

Question

Can you also explain how you know when you use before reaction and after reaction as opposed to an ice chart for these problems. My teacher had gone back and forth with that when she was doing an example of this but I couldn't make sense of how she knew when to use which. Thanks!

1. Consider the titration of 50.0 ml. of 0.200 M HONH2 (K, by 0.100 M IINOh. Calulafe the pll of the resulting solution afteth following volumes of liINO. have been added. base acid con. acio conj. Base a. 0.0 mL b. 50.0 mL c. 100.0 ml d. 125.0 mL

Explanation / Answer

a) pH of weak base = 14 - (1/2(pkb-logC))

pkb = - logkb = -log(1.1*10^-8) = 7.96

C = concentration of weak base = 0.2

pH = 14 - (1/2(7.96-log0.2))

pH = 9.67

b) no of mol of HONH2 = 50*0.2 = 10 mmol

   no of mol of HNO3 added = 50*0.1 = 5 mmol

pH = 14 - (pkb+log(acid/base-acid))

     = 14 - (7.96+log(5/5))

     = 6.04

c) no of mol of HONH2 = 50*0.2 = 10 mmol

   no of mol of HNO3 added = 100*0.1 = 10 mmol

   concentration of salt = 10/150 = 0.0667 M

pH = 7-1/2(pkb+logC)

     = 7-1/2(7.96+log0.0667)

     = 3.6

d) no of mol of HONH2 = 50*0.2 = 10 mmol

   no of mol of HNO3 added = 125*0.1 = 12.5 mmol

concentration of excess HNO3 = (12.5-10)/175 = 0.0143 M

pH = -log(H3O+)

     = -log0.0143

     = 1.845

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.