[yoyo]

Well, actually two... 

1.) How much heat in kJ must be added to 24.0 g of solid sodium, Na, at 25.0oC to give the liquid at its melting point, 97.8oC? The heat capacity of solid sodium is 28.2 J/(K*mol), and its heat of fusion is 2.60 kJ/mol.
2.) The total pressure of 1 L of vapor over liquid acetic acid at 71.3oC is 146 mmHg. If the density of the vapor is 0.789 g/L, what is the mole fraction of dimer in the vapor?

Thank you.

[macman104]

You need to show some work first.  We are not here to do your work for you.

[macman104]

Do you know the equation

q=cm :delta: T?

This is a two step question:

1)  Calculate the energy for heating the sodium to it's melting point
2)  Calculate the energy for melting the sodium

What is :delta: T if the sodium is heated from 25.0° to 97.8°C?
Once the sodium is at 97.8°C, you know it takes 2.60kJ/mol to melt it.  How many moles do you have if you have 24.0g of Na?  How many kJ do you need to melt that many moles (using the value above).

[raffster2]

all it is is simple stoichiometry.. you don't even need the equations if you know how to make units cancel