What causes burns when in contact with hot water? As I understand it thermal energy (heat) is simply a measure of the kinetic energy of an object (For example : water).Hot water is simply water with a larger kinetic energy in its molecules,  right ?
So how do my hands get burned if I immerse them in hot water ? Do the particles collide with my hand and produce burns ?
PS : I may have a conpletely wrong understanding of how heat works . 
 A: Yes, temperature is generally a measure of the average translational kinetic energy of the molecules of an object.
Skin burns occur when the combination of the temperature on the skin and the duration of the exposure of the skin to that temperature exceed the threshold of burn. 
Given a solid, liquid (e.g. water), and gas at the same temperature in contact with the skin, a burn will generally occur first (in time) with the solid, followed by the liquid, and then the gas, due to the relative heat transfer rates (conduction and convection). 
So yes your skin can get burned due to exposure to water as well as a gas.  It will be less severe if you are in contact for the same amount of time with a gas than than with the water, but more severe if you were in contact with a solid at the same temperature,
Hope this helps
A: It should be noted that this question is not that much about heat, as about biochemistry. The actual damage to living tissues is not caused by kinetic "bombardment" by fast molecules, but proteins permanently switching to a different spatial conformation, which is favored at higher temperatures.
This explains why 310 Kelvin water feels fine, but 320 Kelvin (i.e. 47 °C) water burns.
Unlike people, certain bacteria contain only proteins that do not undergo denaturation so easily, so they happily live even at 140 °C.
