The chemical reaction that causes iron to corrode in air is given by 4Fe(s)+3O2(

Question

The chemical reaction that causes iron to corrode in air is given by 4Fe(s)+3O2(g)2Fe2O3(s)

and

rH = 1684 kJ mol1

rS = 543.7 J K1 mol1

a) What is the standard Gibbs energy change for this reaction? Assume the commonly used standard reference temperature of 298 K.

b) What is the Gibbs energy for this reaction at 3652 K ? Assume that rH and rS do not change with temperature.

c) The standard Gibbs energy change, rG, applies only when the reactants and products are in their standard states. Assume that the above corrosion reaction is carried out in a flask where the reactants and products are in their standard states and the values of rH and rS do not change with temperature.

At what temperature, Teq, do the forward and reverse corrosion reactions occur in equilibrium?

Explanation / Answer

dGo = dHo - TdSo is formula

a) dGo = - 1684 - ( 298)( -0.5437)                           ( dSo and dHo units must be same KJ)

             =   -1522 KJ /mol

b) dGo = -1684 -( 3652) ( -0.5437)

           = 301.6KJ/mol

c)   at equilibrium dGo = 0

hence dHo - TdSo = 0

dHo = TdSo

-1684 = Teq x ( -0.5437)

Teq = 3097.3 K

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.