why water will boil over 100 celcius when it's added with salt? Is there any chemical changes?

Answer 1

review the colligative property....
any soluble material will make the boiling point of any liquid higher, i.e boiling point elevation....why?
Boiling point can be defined in terms of the vapor pressure of the solvent. It is the temperature at which the vapor pressure of the liquid or solvent in a solution is equal to the external pressure. Since vapor pressure increases with increasing temperature, increasing teh temperature until the vapor pressure reaches the external pressure will allow the boiling to occur. We have seen in Raoult's Law that increasing the solute in a solution will depress the vapor pressure. This would result in having to increase the temperature even higher so that the depressed vapor pressure might become equal to the external pressure. In other words from a molecular view we might expect the boiling point to be elevated when solute is increased in a solution.

best answer?

Answer 2

actually, i did not know the answer i searched in the net and i found that. i hope it will help you.......


when As soon as any of the salt dissolves in the water, the boiling point of
the water
will begin to rise -- by about one half degree Celsius for every 58 grams
of salt
dissolved per kilogram of water. In fact, any non-volatile soluble
substance will
raise the boiling point of water. That is why antifreeze (ethylene glycol)
provides boiling protection in winter as it simultaneously provides freezing
protection in the summer.

Referring to the specific situation you described: I will assume that the rather
small amount of salt added (relative to the much larger volume of water)will be
completely dissolved well before ebulliation commences. If so, the salted water
will require more exposure to the heat before boiling than would the distilled
water. So the salted water "boils slower" than the distilled water. Nevertheless,
under these real-world conditions of low salt concentration, it would be
difficult to tell which pot boiled first.

Consider this experiment -- just do not do it: Bring two pots of plain water to
near boiling and then toss salt in one of them. The pot receiving the salt will
likely explode into violent boiling because the salt crystals provided nucleation
sites that would allow the water to vaporize as the salt fell through the
superheated liquid. Same thing would happen is you used fine sand. Under those
conditions, the salted water wins. However, that is not (or should not be)
the way things are done.

Answer 3

this is because you added a foreign body to the water. salt is in fact Sodium chloride. when it melts in the water it acts as an impurity and hence the boiling point rises