Problems

DAY 3 TITRATION PROBLEMS

•         A) What is the volume if .5 L of 4 N base is added to 2 N acid?

•         B) What is the concentration if 100 ml of 1 N base is added to 10 ml of acid?

•         C) What is the volume if 500 cm3 of 2 M base is added to 2.5 M acid?

•         D) What is the concentration if 5 ml of 2 m acid is added to base that started at 16 ml and ended at 6 ml?

ANSWERS

•         A) What is the volume if .5 L of 4 N base is added to 2 N acid?

•         CAVA=CBVB

•         2N(VA)= 4 N(.5 L)

•         VA=1 L

 •         B) What is the concentration if 100 ml of 1 N base is added to 10 ml of acid?

•         CAVA=CBVB

•         (CA) 10 ml = 1 N(100ml)

•         CA= 10 N

       C) What is the volume if 500 cm3 of 2 M base is added to 2.5 M acid?

•         CAVA=CBVB

•         2.5 M(VA)= 2 M(500 cm3)

•         VA=400 cm3

 D) What is the concentration if 5 ml of 2 m acid is added to base that started at 16 ml and ended at 6 ml?

•         CAVA=CBVB

•         16-6 = 10 ml

•         (CA) 10 ml = 2 m(5 ml)

•         CA= 1 m

DAY 3

Calculate the pH, pOH, [OH-],[H+] and indicate if it is an acid, base, or neutral.

•         A) pH = 5

•         B) pOH = 10

•         C) [H+] = 1 X 10-8.

•         D) [OH-] = 1 X 10-13.

ANSWERS DAY 3

Calculate the pH, pOH, [OH-],[H+] and indicate if it is an acid, base, or neutral.

•         A) pH = 5

•         pOH = 14-5 =9

•         [H+] = inv log of 5 = 1 X 10-5.

•         [OH-]= inv log of 9 = 1 X 10-9

•         pH is less than 7, so it is an acid

•         B) pOH = 10

•         pH = 14-10 =4

•         [H+] = inv log of 4 = 1 X 10-4.

•         [OH-]= inv log of 10 = 1 X 10-10

•         pH is less than 7, so it is an acid.

•         C) [H+] = 1 X 10-8.

•         [OH-] [H+] = 1 X 10-14

•          [OH-] = 1 X 10-14/ 1 X 10-8

•          [OH-]= 1 X 10-6

•         pH= 8

•         pOH=6

•         pH is more than 7, so it is base.

•         D) [OH-] = 1 X 10-13.

•         [OH-] [H+] = 1 X 10-14

•          [H+] = 1 X 10-14/ 1 X 10-13

•          [H+] =1 X 10-1

•         pH= 1

•         pOH=13

•         pH is less than 7, so it is an acid.

Day 3

•         A) HCl + KOH → KCl   + H2O

•         B) H3PO4 + H2O →H3O+ + HPO4-2

•         C) HNO3  + H2O ← NO3-+ H3O+

•         D) CaBr2 + H2O ← HBr + Ca(OH)2

ANSWERS

•         A) HCl + KOH →  KCl   + H2O

•              Acid   Base     C.B.  C.A

•         Balanced

•         B) H3PO4 + 2 H2O →2 H3O+ + HPO4-2

           Acid      Base       C.A         C.B.

•         C) HNO3  + H2O ← NO3-+ H3O+

           C.A.      C.B  Base     Acid

Balanced

•         D) CaBr2 + 2 H2O ← 2HBr + Ca(OH)2

C.B.        C.A        Acid    Base