Enthalpy change question? Watch

Ash_94
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The standard enthalpy changes of formation of iron(II) oxide, FeO(s), and aluminium oxide,
Al2O3(s), are –266 kJ mol–1 and –1676 kJ mol–1
respectively.

What is the enthalpy change under standard conditions for the following reaction?
3FeO(s) + 2Al (s)  3Fe(s) + Al 2O3(s)?

Please Explain!
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Plato's Trousers
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you need to construct a Hess diagram. Put your elements at the bottom and your reaction at the top. Now one arrow up from the elements to the reactants and another arrow up to the products.

Now, see how many times you have to multiply your delta Hf to generate the right number of molecules of reactants and products. Reverse the direction of the left hand arrow (the one to the reactants) and therefore the sign of delta H.

Now simply add your delta H values and hey presto!

(blimey, never had to explain a Hess cycle in words before!)
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Plato's Trousers
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(Original post by Ash_94)
The standard enthalpy changes of formation of iron(II) oxide, FeO(s), and aluminium oxide,
Al2O3(s), are –266 kJ mol–1 and –1676 kJ mol–1
respectively.

What is the enthalpy change under standard conditions for the following reaction?
3FeO(s) + 2Al (s) 3Fe(s) + Al 2O3(s)?

Please Explain!
so did you manage this? Here is a sketch that might help you visualise it.
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