Molar enthelpy heat of vaporization

  • Thread starter Thread starter GLprincess02
  • Start date Start date
  • Tags Tags
    Heat Vaporization
Click For Summary
SUMMARY

The discussion focuses on calculating the total energy required to heat and vaporize a 23 g sample of ethanol (C2H5OH) starting from 12 degrees C to its boiling point at 78.29 degrees C. The molar enthalpy heat of vaporization for ethanol is established at 35.56 kJ/mol, and the specific heat capacity is noted as 2.44 J/gK. The solution involves two parts: first, calculating the thermal energy needed to reach the boiling point using the formula q=mass x specific heat x change in temperature, and second, applying the heat of vaporization for the phase change from liquid to gas. Attention to unit conversion between grams and moles is crucial for accurate calculations.

PREREQUISITES
  • Understanding of molar enthalpy heat of vaporization
  • Knowledge of specific heat capacity
  • Familiarity with phase changes in thermodynamics
  • Ability to perform unit conversions between grams and moles
NEXT STEPS
  • Calculate thermal energy using the formula q=mass x specific heat x change in temperature
  • Study the concept of molar enthalpy and its applications in thermodynamics
  • Learn about phase changes and their associated energy requirements
  • Review unit conversion techniques for mass and moles in thermodynamic calculations
USEFUL FOR

Chemistry students, educators, and professionals involved in thermodynamics and energy calculations, particularly those focusing on phase changes and heat transfer in substances like ethanol.

GLprincess02
Messages
50
Reaction score
0

Homework Statement


Ethanol boils at a temp. of 78.29 degrees C. What amount of energy, in joules, is necessary to heat to boiling and then completely vaporize a 23 g sample of ethanol initially at 12 degrees C?


Homework Equations


q=mass x constant x change in temp ?


The Attempt at a Solution


I know that the molar enthalpy heat of vaporization is 35.56 kJ/mol and the specific heat of ethanol (C2H5OH) is approximately constant at 2.44 J/gK. However, I am unsure of what to do with these numbers or even which equation to use. Any help at all will be appreciated!
 
Physics news on Phys.org
You can consider this in two parts: the first part is the thermal energy needed to bring the ethanol from 12 degrees to its boiling point. You can use the equation you posted for this. Then you must consider the heat of vaporization when the ethanol undergoes the phase change to the gas state. You should be able to find what you need to do this in your textbook. Give that a try.

Caution: be careful of your units when doing the calculations, since you have quantities expressed in both grams and moles.
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 131 ·
5
Replies
131
Views
11K
  • · Replies 19 ·
Replies
19
Views
4K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 1 ·
Replies
1
Views
14K
  • · Replies 3 ·
Replies
3
Views
6K
Replies
1
Views
3K