# Problem: Consider the following reaction:2Mg(s) + O2 (g) → 2MgO(s) ΔH = - 1204How many kilojoules of heat are absorbed when 40.5 g of MgO(s) is decomposed into Mg(s) and O2 (g) at constant pressure?

###### FREE Expert Solution

We are asked how many kilojoules of heat are absorbed when 40.5 g of MgO(s) is decomposed into Mg(s) and O2 (g) at constant pressure

Molar Mass MgO = 40.31 g/mol

We are asked for the heat absorbed so the ΔH should be positive.

86% (103 ratings) ###### Problem Details

Consider the following reaction:
2Mg(s) + O2 (g) → 2MgO(s) ΔH = - 1204

How many kilojoules of heat are absorbed when 40.5 g of MgO(s) is decomposed into Mg(s) and O2 (g) at constant pressure?

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