39. Titration of strong acids and bases

Question 1

Summary the titration of HCl solution (known concentration) with NaOH solution (unknown concentration)

Answer 1

A strong base of known concentration (0.1 N NaOH) is added to a solution of a strong acid (HCl) of unknown concentration until the equivalence point gets marked by the color change of the indicator

Question 2

A strong base of known concentration (0.1 N NaOH) is added to a solution of a strong acid (HCl) of unknown concentration until the equivalence point gets marked by the color change of the indicator.

Write equations for Dissociation of strong acid and base

Answer 2

HCl → Cl- + H+

NaOH → Na+ + OH-

HCl+NaOH → Cl- +Na++H2O

Question 3

A strong base of known concentration (0.1 N NaOH) is added to a solution of a strong acid (HCl) of unknown concentration.

Which pH indicator is used? describe its properties.

Answer 3

Methyl orange

• Methyl orange changes colour from red to yellow in an aqueous acidic solution.
• effective pH range as
  
  • pH 3.1 to pH 4.4.

Question 4

Principles of the calculation for titration of strong acids and bases

Answer 4

n(H+)= n(OH-) = c1 x v1= c2 x v2

• c1 is the concentration of the titrating solution (known),
• v1 is the needed volume of the titrating solution (measured)
• c2 is the concentration of the unknown solution to get titrated (to be calculated)
• v2 is the known volume of the unknown solution to get titrated.

Question 5

Can water form within titrated solution? How?

Answer 5

Protons react with hydroxide ions to form water:

H+ + OH- → H2O