[orgo814]

This is a tricky question or so it seems: (d= delta)

The standard Gibbs energy change, dG, for a certain chemical reaction is -10 kJ/mol. What is the equilibrium constant at 300 K?

So I thought this would be easy... dG= -RTlnK. But they gave me standard dG. I need to find the dG at 300 K in order to do this problem. At first I thought maybe getting K for the standard (298 K) reaction and then using van't hoff equation to find K at 300 K but I have no way of finding out dH when I don't know dS or the actual reaction. Please help

[mjc123]

"Standard ΔG" means standard conditions at a specified temperature, not necessarily 298K. If there is no other information in the question, it means standard ΔG at 300K. Though a better way to express it would have been:
"The standard Gibbs energy change, dG, at 300K for a certain chemical reaction is -10 kJ/mol. What is the equilibrium constant?"

[orgo814]

I calculated it that way but did not get right answer. Supposedly right answer is 55. I get 0.018

[Yggdrasil]

When I plug in those numbers, I get K = 55.  You may be having problems remembering the negative signs in your equations.  For example, ΔG for the reaction is negative.  Would you expect the equilibrium constant to be > 1 or < 1?

[orgo814]

Yea you're right I missed the negative sign. Thanks