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Schematic Diagram of Energy Changes

Fe2O3(s) + 2Al(s)  Al2O3(s) + 2Fe(l) Clicker Question Given that ΔH°fusion for Fe(s) = 13.6 kJ/mol and the following data: Fe2O3(s) Al2O3(s) ΔHf°(kJ/mol) –826.0 –1676.0   Determine ΔH°rxn (kJ) for the thermite reaction (at constant temperature) as represented by the equation: Fe2O3(s) + 2Al(s)  Al2O3(s) + 2Fe(l) a) –822.8 b) –836.4 c) –850.0 d) –863.6 e) –877.2

Chapter 9: Problem #117 This problem is an application of Hess’s law, although it may not be obvious upon reading it.

Clicker Question What is the smallest number of ice cubes at 0°C, each containing one mole of water, necessary to cool 500.0 g of liquid water initially at 20°C to 0°C at 1.00 atm? Assume for this problem that H and Cp are temperature independent. ΔHf° = -285.6 kJ/mol of H2O(l) ΔHf° = -291.6 kJ/mol of H2O(s) Cp = 75.3 J/molK for H2O(l) a) 1 b) 7 c) 14 d) 15 e) 126