Question

what do you observe before and after adding MnO2 in the chemical reaction​

Answer 1

Answer:

If manganese dioxide is added to hydrogen peroxide,then hydrogen peroxide decomposes into two moles of water and one mole of oxygen.Here MnO2 acts as a catalyst.

H2O2------>2H2O+O2 in the presence of MnO2 catalyst and it is a slightly exothermic reaction.

Answer 2

Hydrogen peroxide, H2O2, decomposes naturally at a very slow rate to form oxygen gas and water.

When manganese dioxide, MnO2, is added to a solution of hydrogen peroxide, the rate of the reaction increases significantly. Manganese dioxide acts as a catalyst for the decomposition of hydrogen peroxide, meaning that it is not consumed in the reaction.

What the manganese dioxide does is it lowers the activation energy of the reaction from approximately 75 kJ/mol to a little under 60 kJ/mol.

This allows more molecules of hydrogen peroxide to undergo decomposition in a shorter period of time. The balanced chemical equation for this reaction looks like this

2H2O2(aq)——MnO2(s)—→2H2O(l)+O2(g)

Or

MnO2 + 2H2O2 --> MnO2 + O2 + 2H2O

2H2O2 --> O2 + 2H2O

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Manganese dioxide is written above the arrow (you'll sometimes see it written under the arrow) because it is not being consumed in the reaction.

Hope this helps you.

Correct me if I'm wrong.