So I thought that for Gibbs' free energy, voltage, enthalpy, and entropy you were supposed to use 298 instead of 273 for the temperature. Why did they use 273 (STP conditions) in the problem?

So I thought that for Gibbs' free energy, voltage, enthalpy, and entropy you were supposed to use 298 instead of 273 for the temperature. Why did they use 273 (STP conditions) in the problem?

thats only under standard conditions which is room temp 25C. This is at -20 and all we're doing is converting Celcius to K.

so you only use it when they specifically state that it's under standard conditions?

yes