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THIS IS ONE QUESTION, 3 PARTS!! EXACTLY HOW IT IS ASKED. The chemical reaction t

ID: 936413 • Letter: T

Question

THIS IS ONE QUESTION, 3 PARTS!! EXACTLY HOW IT IS ASKED.

The chemical reaction that causes chromium to corrode in air is given by

4Cr+3O2?2Cr2O3

in which at 298 K

A)What is the standard Gibbs free energy for this reaction? Assume the commonly used standard reference temperature of 298 K. Include units ?G?rxn=?

b)What is the Gibbs free energy for this reaction at 4717K ? Assume that ?H and ?S do not change with temperature.?Grxn =?

c)At what temperature Teq do the forward and reverse corrosion reactions occur in equilibrium? Teq=?

?H?rxn = ?2256 kJ ?S?rxn = ?549.1 J/K

Explanation / Answer

A) DG0= DH0 -TDS0---> DG0=-2256KJ - 298K x -0.5491KJ/K= -2092.4 KJ

B) DG= DH -TDS---> DG=-2256KJ - 4717K x -0.5491KJ/K= 334.1KJ

In this case we use DH0 and DS0 as DH and DS because the question says that they don