Why does the hydrogen bond in water cause the boiling point of water to be higher than the boiling point ofH2S

Question

It's related to chemistry & boiling points if that helps....

Answer 1

Hydrogen bonds are a bit weaker than covalent bonds. Because they are fairly strong, it takes more energy to break these bonds when heating, thus increasing the boiling point of the substance, in your case, water. Hydrogen bonding doesn't occur in H2S (only weak bonds like dispersion forces, etc.), so its boiling point will be lower than water.

Answer 2

it has nothing to do with the density. it has to do with the vapor pressure. Put simply: at any time, there are water molecules that want to leave the water and become the air, and there's water vapor in the air trying to condense back into the water. both these happen at the same speed, and it's called equilibrium. Now, the hotter the water gets, the more water wants to get into the air and evaporate. And the boiling point is simply that where all the water wants to be in the air (vapor pressure= atmospheric pressure). So now, imagine a pot of water (this is much easier when I have a chalk board), the surface of the water is just that: water. But now let's say I put in some salt. Let's say I make the solution 5% salt. so for every molecule of water, I have one NaCl. Well the Na+ and the Cl- will break apart into two seperate things, making it 5% Na, 5% Cl, and 90% water (we're talking by number of things floating around, not by mass. mass is irrelevant here). Now, when it was pure water, water could condense from the atmosphere at any point on the surface, and could leave from the pot from any point on that surface, 'cause it's all water. right? But now if the surface is only 90% water, because 10% of it is salt, then water vapor can still condense anywhere, but liquid water can only leave from 90% of the surface now, so it throws off the equilibrium, lowering the vapor pressure. Since the vapor pressure for any given temperature is lower, it takes a higher temperature to make the vapor pressure equal the atmospheric pressure and make the liquid boil.

Answer 3

Well H2S boils at around -60 C. First you should look at electronegativities. Oxygen is more electronegative than Sulfur. So Oyxgen creates a bigger delocalization of charge densities compared to Sulfur, which induces the strength of its hydrogen bonds to be weaker.

Secondly, electron shielding is much higher in Oxygen, resulting in less electric potential compared to sulfur. The higher potential brought out from sulfur induces the molecules to be more distant from each other.

Ionic radii and relative bond strength/ distance also plays a part in it.