Understanding Enthalpy of Reaction in the Thermite Reaction

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Discussion Overview

The discussion revolves around understanding the enthalpy of reaction in the thermite reaction, specifically the reaction between iron(III) oxide (Fe2O3) and aluminum (Al). Participants are addressing questions related to calculating the heat liberated during the reaction and the implications of Hess's law in this context.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant expresses confusion about how to apply Hess's law to find the enthalpy for the reaction of one mole of Fe2O3 with Al, indicating uncertainty about the relevance of the given enthalpy values.
  • Another participant points out that the final equation presented by the first participant is incorrect and emphasizes the importance of denoting the states of the reactants and products, as well as considering the stoichiometry involved in the enthalpy calculations.
  • A question is raised about whether the reaction can be classified as a single displacement reaction between Al and Fe2O3.
  • A later reply confirms the correct balanced equation for the reaction and encourages the first participant to proceed with their calculations.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct approach to calculating the enthalpy of the reaction, and there are competing views regarding the proper formulation of the reaction equation and the application of Hess's law.

Contextual Notes

There are limitations in the clarity of the enthalpy values provided, including their dependence on the specific stoichiometry of the reactions and the states of the reactants and products. The discussion does not resolve the mathematical steps necessary for the calculations.

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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