Looking at this equation P= (pa*pb)/ (pa+(pb-pa)) ya where pa=vap press a and ya= vap composition a and P= total pressure,it relates vapor pressure mixture to vapor composition. This is derived using the combination of Dalton's and Raoult's laws.
How it looks. basically the thing that tells you how it change. for example if an ice cube was melted (heat), it only changed physically not chemically as the h20 molecules are still there. however lets say you burn woos— you cant get that would back. its ash now and it has changed chemically.
When the concentration is expressed in molality, it is expressed in moles of solute per kilogram of solvent. Since we are given the mass of the solvent, which is water, we can compute for the moles of solute NaNO3.
0.5 m = x mol NaNO3/0.5 kg water
x = 0.25 mol NaNO3
Since the molar mass of NaNO3 is 85 g/mol, the mass is
0.25 mol * 85 g/mol = 21.25 grams NaNO3 needed
Answer:
Heat transferred, Q = 1542.42 J
Explanation:
Given that,
Mass of water, m = 30 grams
Initial temperature, 
Final temperature, 
We need to find the energy transferred. The energy transferred is given by :

c is specific heat of water, c = 4.18 J/g °C
So,

So, 1542.42 J of energy is transferred.