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When we heat a liquid (suppose, water) , it's molecules become energetic and gain more and more kinetic energy hence move away from equilibrium position and volume increases. But, When heat is added, why does the temperature rise until boiling point and then all the energy goes towards breaking bonds? , Why don't the bonds break before boiling point .

Boiling point is pressure dependent. If the pressure of vapour is equal to atmospheric pressure, all the molecules escape the container . In this , what I dont understand is: why the pressure of molecule inside the container called as vapour pressure?, it just the water molecule having more energy. Vapour is formed when the molecule escape the container and spread out in surrounding.

And, why we need to add the extra energy at boiling (latent heat of vaporization)?

I am having trouble to understand this. Pls explain

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Bonds do break before the boiling point. That is why the vapor pressure exists.

As the temperature increases, the amount of breaking increases as well. Imagine that some bonds break in the middle of the pan. The water molecule disconnects and isn't bound as liquid any longer. It would like to take up more space. But the air above the liquid pushes it back down. At low temperatures, the air pressure is stronger and the molecule is pushed back until it rejoins the liquid. If the air pressure were less, the same process would happen, but the air couldn't squeeze it back together.

Breaking the bonds always needs more energy. But below the cooling point, it just isn't happening rapidly enough.

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