Redox titrations are used to determine the amounts of oxidizing and reducing age

Question

Redox titrations are used to determine the amounts of oxidizing and reducing agents in solution. For example, a solution of hydrogen peroxide, H2O2, can be titrated against a solution of potassium permanganate, KMnO4. The following equation represents the reaction:

2KMnO4(aq)+H2O2(aq)+3H2SO4(aq)?O2(g)+2MnSO4(aq)+K2SO4(aq)+4H2O(l)

A certain amount of hydrogen peroxide was dissolved in 100. mL of water and then titrated with 1.68 M KMnO4. What mass of H2O2 was dissolved if the titration required 20.3mL of the KMnO4 solution?

Explanation / Answer

Moles H2SO4 = 0.0207 L x 1.50 M=0.03105

the ratio between H2SO4 and KOH  
H2SO4 + 2 KOH = K2SO4 +2 H2O
is 1 : 2

moles KOH = 2 x 0.03105 =0.0621
molar concentration of KOH = 0.0621 / 0.900 L=0.690 M

moles KMnO4 = 0.0203 L x 1.68 M=0.0341

6 H+ + 2 MnO4- + 5 H2O2 = 2 Mn2+ + 5 O2 + 8 H2O
the ratio between MnO4- and H2O2 is 2 : 5

moles H2O2 = 0.0341 x 5/2 =0.0853
mass H2O2 = 0.0853 mol x 34.014 g/mol= 2.90 g

Related Questions

Navigate

• Browse (All)
• Browse R
• Subjects

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