At what temperature, Teq, do the forward and reverse corrosion reactions occur in equilibrium?
The chemical reaction that causes aluminum to corrode in air is given by
4Al+3O2?2Al2O3
in which at 298 K
?Hrxn? = ?3352 kJ
?Srxn = ?625.1 J/K
What is the standard Gibbs free energy for this reaction? Assume the commonly used standard reference temperature of 298 K?
What is the Gibbs free energy for this reaction at 5975K ? Assume that ?H and ?S do not change with temperature.
At what temperature, Teq, do the forward and reverse corrosion reactions occur in equilibrium?

Respuesta :

Answer:

See explanation below.

Explanation:

We can obtain the Gibb's free energy from the formula;

∆G= ∆H - T∆S

Where;

∆G = change in free energy= the unknown

∆H= change in enthalpy = 3352 kJ

∆S= change in entropy of the solution= 625.1 J/K

T= absolute temperature = 298 K

Substituting values;

∆G= 3352 ×10^3 J - (298 K × 625.1 J/K)

∆G= 3352 ×10^3 J - 186279.8

∆G= 3.16 × 10^6 J

At 5975K,

∆G= ∆H - T∆S

∆G= 3352 ×10^3 J - (5975K × 625.1 J/K)

∆G= 3.352 ×10^6 J - 3.735 × 10^6

∆G= -3.83×10^5 J

At equilibrium, ∆G=0, Teq is given by;

0= 3352 ×10^3 J - (Teq × 625.1 J/K)

0= 3352 ×10^3 - 625.1Teq

625.1Teq = 3352 ×10^3

Teq= 3352 ×10^3/625.1

Teq= 5362.3 K

Standard Gibb's free energy at 298 & 5975K is 3.16×10⁶J and -3.83×10⁵J respectively, and temperature at equilibrium state is 5362.3 K.

How do we calculate standard Gibb's free energy?

Standard Gibb's free energy of any reaction will be calculated as:
∆G° = ∆H° - T∆S°, where

∆G° = change in free energy = to find?

∆H° = change in enthalpy = 3352 kJ = 3,352 × 10³J

∆S° = change in entropy = 625.1 J/K

T = absolute temperature = 298 K

On putting all these values on the above equation, we get

∆G° = (3,352 × 10³) - (298 × 625.1) = 3.16 × 10⁶J

Gibb's free energy at 5,975 K temperature:

∆G° = (3,352 × 10³) - (5,975 × 625.1) = -3.83 × 10⁵J

At the equilibrium state value of Gibb's free energy is zero, so from the equation and given data we can calculate the value of temperature as:

0 = (3352 × 10³)J - (T × 625.1 J/K) = 5362.3 K

Hence required values are 3.16 × 10⁶J, -3.83 × 10⁵J and 5362.3 K.

To know more about Gibb's free energy, visit the below link:

https://brainly.com/question/9908454