Manganese dioxide reacts with aluminum to form aluminum oxide and manganese according to the equation below.

The answer is -1839.5 kJ/mol. This was calculated using the given formula for ΔH. You have to calculate the sum of ΔHf for products and subtract from it the ΔHf of the reactants.

ΔHrxn = (2 mol *-1699.8 kJ/mol) - (3 mol * -520 kJ/mol) where 2 mol Al2O3 and 3 mol MnO2 came from the given reaction. The other reactant and products are in their standard form so their ΔHf is zero.

you need to have a picture of the atom that way we can answer it

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