Question

Calculate the enthalpy change for the thermite reaction: 2Al(s)+Fe2O3(s)→2Fe(s)+Al2O3(s), ΔH∘rxn=−850 kJ when 12.0 mol of Al undergoes the reaction with a stoichiometrically equivalent amount of Fe2O3. Express your answer to three significant figures and include the appropriate units.

Answer 1

Answer: The enthalpy of the reaction for given amount of aluminium will be $-51.0\times 10^2kJ$

Explanation:

We are given:

Moles of aluminium = 12 moles

For the given chemical reaction:

$2Al(s)+Fe_2O_3(s)\rightarrow 2Fe(s)+Al_2O_3(s);\Delta H^o_{rxn}=-850kJ$

By Stoichiometry of the reaction:

If 2 moles of aluminium produces -850 kJ of energy.

Then, 12 moles of aluminium will produce = $\frac{-850kJ}{2mol}\times 12mol=-5100kJ$ of energy.

Converting this into three significant figures, we get:

$\Rightarrow -5100kJ=-51.0\times 10^{2}kJ$

Thus, the enthalpy of the reaction for given amount of aluminium will be $-51.0\times 10^2kJ$