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 17.3 mL of the KMnO4 solution?

Express your answer with the appropriate units.

Explanation / Answer

Answer – Given, [KMnO4] = 1.68 M , volume = 17.3 mL

Volume of H2O2 = 100 mL .

Reaction –

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

For the calculating the mass of H2O2 was dissolved first we need to calculate moles of H2O2

Moles of KMnO4 = 1.68 M * 0.0173 L

                             = 0.0291 moles

From the balanced equation –

2 moles of KMnO4 = 1 moles of H2O2

So, 0.0291 of KMnO4 = ?

= 0.0145 moles of H2O2

So mass of H2O2 = moles of H2O2 * molar mass of H2O2

                             = 0.0145 moles * 34.014 g/mol

                              = 0.494 g

So, 0.494 g of mass of H2O2 was dissolved if the titration required 17.3 mL of the KMnO4 solution.

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