Question

Записать химические реакции качественного определения марганца в металлоломе, содержащем MnO2..

Answer 1

MnO2

вещество коричнево-черного цвета;

нерастворимо в воде;

обладает амфотерными свойствами:

MnO2+2KOH → K2MnO3+H2O

MnO2+2H2SO4 → Mn(SO4)2+2H2O

проявляет, как окислительные, так и восстановительные свойства, в зависимости от кислотных свойств другого взаимодействующего вещества:

2MnO2+3PbO2+6HNO3 → 2HMnO4+3Pb(NO3)2+2H2O (восстановитель)

MnO2+4HCl → MnCl2+Cl2↑+2H2O (окислитель)

Answer 2

Chemical Reactions for Qualitative Determination of Manganese in Metal Scrap Containing MnO2

To qualitatively determine the presence of manganese (Mn) in metal scrap containing manganese dioxide (MnO2), you can use a series of chemical reactions. Here are the steps involved:

1. Reaction with Hydrochloric Acid (HCl): - When manganese dioxide (MnO2) reacts with hydrochloric acid (HCl), it produces chlorine gas (Cl2) and forms manganese chloride (MnCl2) and water (H2O) as products. - The balanced chemical equation for this reaction is: ``` MnO2 + 4HCl → MnCl2 + Cl2 + 2H2O [[1]] ```

2. Oxidation of Manganese(II) to Manganese(IV) with Potassium Permanganate (KMnO4): - Manganese(II) ions (Mn^2+) can be oxidized to manganese(IV) ions (Mn^4+) by potassium permanganate (KMnO4) in an acidic medium. The purple color of the permanganate solution will disappear as it is reduced to colorless manganese(II) ions. - The balanced chemical equation for this reaction is: ``` 5Mn^2+ + 2MnO4^- + 16H+ → 7Mn^4+ + 8H2O [[2]] ```

3. Formation of Manganese(II) Hydroxide Precipitate: - By adding sodium hydroxide (NaOH) to the manganese(II) solution obtained from the previous step, a white precipitate of manganese(II) hydroxide (Mn(OH)2) will form. - The balanced chemical equation for this reaction is: ``` Mn^2+ + 2NaOH → Mn(OH)2 + 2Na+ [[3]] ```

These reactions can be used to qualitatively determine the presence of manganese in metal scrap containing manganese dioxide.

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