Standard State

[Thu Uyen Tran 1B]

When solving for standard enthalpy, everything must be balanced and in its standard state in the reaction. How can we determine if something is in its standard state or not? Also what should we do if something is in fact not in its standard state?

[Jason Liu 1C]

Something is in its standard state when one mole of it is being produced. You can put something into its standard state by dividing both sides of the chemical equation by however much you need to make the product one mole.

[Julian Krzysiak 2K]

Elements are in their standard state when they are in their most stable phase at the temperature of interest, which is usually 25 Celsius, while exposed to a constant pressure of 1 atm (They must also be 1 mole if they are a solution). So you can look at a periodic table at 25 C. and check the phases, unless the problem specifically states the reaction to be occurring at another temperature.