Understanding Enthalpy of Reaction in the Thermite Reaction

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SUMMARY

The thermite reaction, involving the exothermic reaction between iron(III) oxide (Fe2O3) and aluminum (Al), releases significant heat. The balanced equation for the reaction is Fe2O3 + 2Al → Al2O3 + 2Fe, with an enthalpy change (delta H) of -836 kJ for the formation of aluminum oxide. To calculate the heat liberated for one mole of Fe2O3 with Al, Hess's law is applicable. The discussion emphasizes the importance of stoichiometry and proper notation in determining the enthalpy values for the reactions.

PREREQUISITES
  • Understanding of thermodynamic concepts, specifically enthalpy
  • Familiarity with Hess's law and its application
  • Knowledge of stoichiometry in chemical reactions
  • Basic understanding of exothermic reactions and their characteristics
NEXT STEPS
  • Study Hess's law in detail to understand its application in thermochemical equations
  • Learn about enthalpy calculations for various chemical reactions
  • Explore the concept of stoichiometry and its role in chemical equations
  • Investigate the properties and applications of aluminum oxide (Al2O3) in thermite reactions
USEFUL FOR

Chemistry students, educators, and professionals involved in thermodynamics, chemical engineering, and materials science will benefit from this discussion.

forevergone
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I've been having trouble understanding some parts of these questions. The question goes like this:

The "thermite reaction" is highly exothermic. It involves the reaction between Fe2O3 & Al. The reaction produces white-hot, molten iron is a few seconds.
2 Al + 3/2 O2 --> Al2O3 delta H = -1672 kJ
2 Fe + 3/2 O2 --> Fe2O3 delta H = -836 kJ​

a) find the amount of heat liberated in the reaction of one mole of Fe2O3 with Al.
b) find the amount of heat liberated in the reactino of 1 kg of Fe2O3 with Al.
c) how many grams of liquid water could be heated from 0C to 100C by the heat liberated per mole of aluminum oxide?

For a) and b), when I'm trying to find the enthalpy, do I need to apply hess's law to obtain the enthalpy of one mole of Fe2O3 and Al? The part that confuses me is the relevance with Fe2O3 and Al. So far, I've only gotten to figuring out what the target eq'n is.

2 Al + 2 Fe --> Al2O3 + Fe203 delta H = -836kJ​

But after determining the target eq'n, I don't know what to do in terms of Fe2O3 and Al for that one mol and similarly with determining 1 kg.
 
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If they want the reaction of the iron oxide with aluminum (you should denote the states of the molecules/atoms involved), your final equation is incorrect. Write the proper equation, and observe on whether the terms in the enthalpy values for each denoted reaction (kJ/mol, kJ/grams or kJ/mol reaction, kJ/mol Al etc...), the rest should be simple, Don't forget to take into account the stoichiometries.
 
So really, it's just a single displacement rxn then between Al and Fe2O3?
 
yes, Fe2O3 + 2Al → Al2O3 + 2Fe, I'm sure you can take it from here
 

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