I don't get how the intermolecular forces (Hydrogen bonding) relates to the heating curve of water.

Question

I read some stuff on intermolecular force for Hydrogen bonding and it said that the force between water molecules raise the boiling point of water. So would this mean that the heating curve of water would be different? if it is could someone write how it is differentfrom other heating curves except that the boiling point is higher.

OR maybe does this cause a longer process for water to change from a solid to a liquid?

I don't know...

Could someone explain the first question of how they are related.

Thank you

Answer 1

This may not help much but I will try. The reason I say it may not help much is I don't put much stock into "heating curve" as such and the remainder of the question. The bottom line is that whether the heating curve is affected or not, the boiling point of water is higher than expected because of hydrogen bonding. That is because the extra forces acting on water molecules (extra forces being hydrogen bonding) is enough to cause the molecules to require more energy in order to break apart from each other in the liquid state and become vapor molecules. That is reflected in the higher boiling point. It stands to reason then that if hydrogen bonding increases the energy needed for vaporization that it also takes more energy to raise the temperature from say 25 degrees C to 50 degrees C or to 75 degrees C than we might expect. But I don't see that getting into a discussion of how much energy is needed for the heating curve is necessary as long as we know that the energy needed to raise the temperature is mass water x specific heat water x (Tfinal-Tinitial). And that quantifies any change in temperature in which we might be interested. We can calculate the energy required to raise the temperature of one substance by 1 degree versus another substance with hydrogen bonding by 1 degree but in the end we are simply quantifying the m*C*delta T and we knew that all along anyway. I hope this makes sense to you. Technically, I haven't answered your question but philosophically I tried to show it follows from what we already know about the heat laws.