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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: yankeekd25 on April 23, 2009, 11:16:19 AM

Title: Gibbs Free Energy
Post by: yankeekd25 on April 23, 2009, 11:16:19 AM

Consider the reaction

H2(g) + C2H4(g) --> C2H6(g)

Using the standard thermodynamic data in the tables linked above, calculate deltaG for this reaction at 298.15K if the pressure of each gas is 26.89 mm Hg.

delta G for C2H6(g)= -32.8
          for C2H4(g)= 68.2
          for H2 (g)  =  0

What effect does the pressure have the Gibbs free energy calculations?

Title: Re: Gibbs Free Energy
Post by: leve on April 23, 2009, 01:49:55 PM

What can you use the given pressures to calculate?

There are a few equations using deltaG. Which one would you use pressure for?

Title: Re: Gibbs Free Energy
Post by: yankeekd25 on April 26, 2009, 01:32:22 PM

Quote from: leve on April 23, 2009, 01:49:55 PM

What can you use the given pressures to calculate?

There are a few equations using deltaG. Which one would you use pressure for?

Can you use the pressures to find Kp, then use the equilibrium constant, then plug it into the

G= -RT ln k?

Title: Re: Gibbs Free Energy
Post by: joshuaeddy27 on April 29, 2009, 07:15:22 AM

you might try this
(delta)G = (delta)G(std) + RTln(Q)

the delta G changes in relation to the temperature and you can use the partial pressures to figure out the Q.  it doesn't seem like the entire question was posted.