Determine the amount of heat required to convert 46.0 g of ethanol at 25°c to the vapor phase at 78°c. based on the melting and boiling points

the amount of heat required is 6.5kJ

Explanation:

Hi !

To solve this problem follow the steps below

1.Through laboratory tests, thermodynamic tables were developed, these allow to know all the thermodynamic properties of a substance (entropy, enthalpy, pressure, specific volume, internal energy etc ..)

through prior knowledge of two other properties such as pressure and temperature.

2. use thermodynamic tables to determine enthalpies in the initial and final states using temperatures and atmospheric pressure, remember that enthalpies already have energy counts by phase change

h1=Enthalpy(Ethanol;T=25C;P=101,325kPa) =258.7KJ/kg

h2=Enthalpy(Ethanol;T=78C;P=101,325kPa)=400.1 KJ/kg.

3. uses the first law of thermodynamics that states that the energy that enters a system is the same that must come out, we can infer then that heat is equal to the product of mass due to the difference in enthalpies

Q=m(h2-h1)

m=mass=46g=0.046kg

Q=0.046kg(400.1 KJ/kg.-258.7KJ/kg)=6.5kJ

the amount of heat required is 6.5kJ

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