Calculate the standard enthalpy of the reaction, ΔH∘rxn, for the thermite reaction:
2Al(s)+Fe2O3(s)→2Fe(s)+Al2O3(s)
Elements in their standard state have an enthalpy of formation value of zero. The standard enthalpies of formation of Fe2O3 and Al2O3 are
ΔH∘f of Fe2O3(s)=−825.5 kJ/molΔH∘f of Al2O3(s)=−1675 kJ/mol
Express your answer to three significant figures and include the appropriate units.

Respuesta :

Answer:

The answer to your question is ΔH rxn = - 849.5 kJ/mol

Explanation:

Reaction

                   2Al(s)  + Fe₂O₃ (s)   ⇒   2Fe (s)   +  Al₂O₃ (s)

Enthalpy of reaction

ΔHrxn =  ∑ H products - ∑ H reactants

ΔHrxn = ∑( H (Al₂O₃) + H (Fe)  - ∑ ( H Fe₂O₃ + H Al)

ΔHrxn = [-1675 + 0] - [ -825.5 + 0]

ΔHrxn = -1675 + 825.5

ΔHrxn = - 849.5 kJ/mol

The standard enthalpy of reaction can be defined as the reaction change that takes place when there has been transfer of energy in the reactions.

The standard enthalpy of reaction ([tex]\rm \bold{\Delta H_r_x_n}[/tex]) can be given by:

[tex]\rm \bold{\Delta H_r_x_n}[/tex] = Enthalpy of formation of products - Enthalpy of formation of reactants

The enthalpy of formation of reactants :

= 2 [tex]\times[/tex] [tex]\rm \Delta H_f\;Al[/tex] + 1 [tex]\rm \times\;\Delta H_f\;Fe_2O_3[/tex]

Since Al is in a standard state, the enthalpy of formation is 0.

= 0 + (-825.5 kJ/mol)

= -825.5 kJ/mol

The enthalpy of formation of products:

=  2 [tex]\times[/tex] [tex]\rm \Delta H_f\;Fe[/tex] + 1 [tex]\rm \times\;\Delta H_f\;Al_2O_3[/tex]

Since Fe is in a standard state, the enthalpy of formation is 0.

= 0 + (-1675 kJ/mol.)

= -1675 kJ/mol

[tex]\rm \bold{\Delta H_r_x_n}[/tex] = -1675 kJ/mol - (-825.5 kJ/mol)

[tex]\rm \bold{\Delta H_r_x_n}[/tex] = -1675 kJ/mol + 825.5 kJ/mol

[tex]\rm \bold{\Delta H_r_x_n}[/tex] = -849.5 kJ/mol.

The standard enthalpy for the given reaction has been -849.5 kJ/mol.

For more information about the standard enthalpy, refer to the link:

https://brainly.com/question/10583725