Gibbs Free Energy for non-standard conditions

[sgstudent]

ΔG=ΔG°+RTlnQ are for reactions that are not under standard conditions. What does it mean under non-standard conditions for the ΔG?

And what is the Q in this case? Is it Qp where it is based on the partial pressure of the gas or Qc which is based on the concentration?

Thanks

 

[DrDu]

Standard conditions are a convention and differ for solids liquids and gasses, as well as for solutes and solvents. Also, in biological systems other standard conditions are chosen than in chemistry.
A gas is under standard conditions when its fugacity (which is equal to its partial pressure in a good approximation for not too high pressures) is 1 bar. For a solution, standard condition of the solute is an activity of 1 mol/kg. For the solvent, the standard state is the pure solvent. For a solid, the pure solid.