Heat and temperature Please See THIS

[Diniz Noronha]

Hi I am a student at Brazil and I have a question.

Is possible this phenomenon: A tube passes steam from a container of boiling water into a saturated aqueous salt solution. Can it be heated by the steam to a temperature greater than 100°C ?

 

[Danger]

Only if you provide some means of superheating the steam, such as boiling the water under high pressure or passing the steam tube through a secondary heat source. You can't transfer more heat from a substance than it contains.
If you mean, can the solution remain liquid at greater than 100° C, I think that the water would just boil off and leave the salt behind. Someone better check me on that, though.

 

[Hootenanny]

I agree. As I understand it, the liquid may well be at a temperature greater than 373K due to ions dissolved in solution but the steam can only ever be at 373K unless the stream itself is heated in a secondary process.

 

[Danger]

I just double-checked, and I was wrong about solutions. Since the salt lowers the vapour pressure of the water, saline has a boiling point above that of pure water. In that case, superheated steam could indeed raise its temperature higher than 100° C and still let it remain a liquid. You still can't raise the temperature of the initial steam higher than that just by boiling water, though.

 

[Bystander]

I just double-checked, and I was wrong about solutions. Since the salt lowers the vapour pressure of the water, saline has a boiling point above that of pure water. In that case, superheated steam could indeed raise its temperature higher than 100° C and still let it remain a liquid. You still can't raise the temperature of the initial steam higher than that just by boiling water, though.

First two guesses don't count. Can you answer correctly with number three?

 

[Danger]

Okay, what did I miss this time?

 

[Bystander]

Enthalpy of dilution.

 

[Danger]

In English, please.
Remember, I never finished high-school.

 

[Bystander]

Sol'n(pick your solute, solvent, and concentration; T) + Solvent(same; T) mixed to form Sol'n(same solute, same solvent, new concentration, less than original) PLUS enthalpy of dilution. Positive, negative, large, small. Not to be confused with enthalpy of solution