Ethanol (C2H5OH) melts at –114 °C and boils at 78 °C. The enthalpy of fusion of ethanol is 5.02 kJ/mol, and its enthalpy of vaporization is 38.56 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/g-K and 2.3 J/g-K, respectively. The average specific heat of gaseous ethanol is about 1.80 J/g-K. a. How much heat is required to convert 35.0 g of ethanol at 27 °C to the vapor phase at 120 °C? b. How much heat is required to convert the same amount of ethanol at –120 °C to the vapor phase at 120 °C?

First question

Second  question  

Explanation:

From the question we are told that

     The melting point of Ethanol is  

      The boiling point of Ethanol is  

       The enthalpy of fusion of Ethanol is

        The enthalpy of vaporization  of Ethanol is

         The specific heat of solid Ethanol is  

          The specific heat of liquid  Ethanol is

           The mass of the Ethanol given is  

Considering the first question

           The initial  temperature is

             The final  temperature is  

Generally the heat required too raise the Ethanol to its boiling point is mathematically represented as

=>      

=>      

Genially the number of moles of Ethanol given is mathematically represented as

Here Z  is the molar mass of Ethanol  with value  

So

=>      

Generally the heat of vaporization of the Ethanol is mathematically represented as

=>        

=>        

Generally the heat required too raise the Ethanol from  its boiling point to    is  mathematically represented as

=>    

=>    

Generally the total heat required is  

=>  

=>  

Considering the second question

           The initial  temperature is

             The final  temperature is  

Generally the heat required too raise the Ethanol to its melting  point is mathematically represented as

=>      

=>      

Generally the heat of fusion  of the Ethanol is mathematically represented as

=>        

=>        

Generally the heat required too raise the Ethanol to its boiling point is mathematically represented as

=>      

=>      

Generally the heat of vaporization of the Ethanol is mathematically represented as

=>        

=>        

Generally the heat required too raise the Ethanol from  its boiling point to    is  mathematically represented as

=>    

=>    

Generally the total heat required is  

=>  

=>