# What is absolute molar entropy and how do I use it?

Apparently, under standard conditions, the absolute molar entropy of liquid water is $S^{\ominus}_m = 69.9 \frac{J}{mol*K}$. What is absolute molar entropy? And would it change under different conditions (like a different temperature)?

I was asked to find the change in molar entropy induced by heating the system enough that the resulting vapor has a temperature of 400 K.

My guess for solving this problem would be to simply calculate the amount of energy need to raise 1 mole of water to boiling from 0C (using heat capacity of water). Then use the enthalpy of vaporization to calculate the amount of energy needed to vaporize that water. Then find the amount of energy to raise 1 mole of steam to 400 K (using steam heat capacity). I'm not sure how to solve this problem using the absolute molar entropy of liquid water.