Does the boiling water change if salt is added?

Answer 1

There are several reasons why the boiling point changes when salt is added to water.

Firstly you have to understand the heat capacity (how much heat is needed to heat a substance) of water and salt. Water has a high heat capacity which means that it needs a lot of heat to warm the liquid up. However, when salt is added to water the heat capacity is lower, therefore less heat is needed to warm the liquid up.

Secondly, you have to observe the amount of salt added to water. So, if you compare 100ml of water to 100ml of salt water - what percentage of this solution is salt? (say 40% salt and 60% water). This is important because, the heat capacity of the 60% of the water in salt water, is 40% less than the 100% water, so it takes less energy to heat up the mixture.

Anyway, going back to the question, yes the boiling point does change slightly when salt is added. In fact the boiling point of water will increase with any impurity in the water. With Salty water the boiling point increases and freezing point decreases (but there is no definite boiling point for salt water because it depends on the ratio of salt to water).

Thirdly, when you add salt to water you change the molecular-level of water (also called colligative property). The concentration of water in salt water is less, so the vapour pressure of salt water is less and that's why the temperature must increase.

Lastly, when salt is added to H2O, the NaCl (salt- Sodium Chloride) interferes with the H and the O. This stops the liquid from behaving the way it usually does. Like when you freeze salt water...

Answer 2

When a solute (salt) is added to a solvent (water), the melting point decreases and the boiling point increases. The boiling point increases because for boiling to occur, the salt must come out of solution (undissolve). This requires a decrease in entropy. Effectively, it requires energy for the salt to come out of solution, so more heat (energy) must be added to the solution before the salt comes out of solution, allowing the water to boil.

Answer 3

Please answer quickly - I need an answer by 01/02/11

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Yes, there is a change in the temperature when salt is heated to boiling temperature. The temperature increases from 100 degree celsius to 102 degree celsius.

Answer 4

The water molecules find themselves more attracted to the salt ions than pure water is to itself. In order to boil, the water molecules must gain enough kinetic energy to compensate for the greater intermolecular forces produced by the dissolved salt.

Answer 5

For dissolutions there are two important energies that have to be regarded:

the lattice energy that keeps the ions of the salt together and

the enthalpie of dissolution that is freed when an ion is solvated

When you dissolve a salt in water you have to break the ions away from the crystal chunk and maybe you know salt (NaCl) is made of positive Na+ and negative Cl- ions - positive and negative are attracted to each other (like magnets) and for a break up you need energy (just like magnets, too)

When the ions are released, they are getting a kind of sleave of water molecules which releases some energy (the enthalpie of dissolution + hydration)

Now there are three possibilities:

1. The lattice energy equals the enthalpie of dissolution - so no change in temperature occurs

2. The enthalpie of dissolution is higher than the lattice energy - so the energy is freed in the form of warming

3. The case of NaCl: the lattice energy is (slightly) higher - so the system takes the energy that is missing for the break up from the liquid around and cools down your boiling water

Answer 6

Yes, adding salt to water increases its boiling point. This is due to the fact that the presence of salt lowers the vapor pressure of the water, requiring a higher temperature to boil.

Answer 7

When you add salt to boiling water the boiling point is increased.
The boiling point and freezing point of water raises when you add salt.

Answer 8

salt raises the boiling point