A 0.2 g sample of pyrolusite is analyzed for manganese content as follows. Add 50.0 mL of 0.1 M solution of ferrous ammonium sulfate to reduce the MnO2 to Mn2 . After reduction is complete, the excess ferrous ion is titrated in acid solution with 0.02 M KMnO4, requiring 15.0 mL. Calculate the percent manganese in the sample as Mn3O4.

66.7%

Explanation:

The reaction for the titration of the excess ferrous ion is:

We calculate the moles of Fe⁺² from the used moles of KMnO₄:

Then we substract those 0.30 mmol from the original amount used:

The reaction between ferrous ammonium sulfate and MnO₂ is:

So we convert those 3.5 mmol Fe⁺² that were used in this reaction to MnO₂ moles:

Then we convert MnO₂ to Mn₃O₄, using the reaction:

Finally we convert Mn₃O₄ moles to grams:

And calculate the percent

answer: -

reaction:

na + cl ⇌ nacl

balanced chemical equation:

na + 2cl ⇌ nacl2

sodium + clorine goes to form sodium chloride (table salt).

the product is nacl2.

and the reactants are na and cl.

(note: if you don’t know what ⇌ means, read below: -

⇌(double head arrow) means reversible reaction).