I really don't understand this question. How do I work it out?
Pure acetic acid, HC2H3O2 has the following characteristics:
mp = 14.6 degrees C
bp = 167.3 degrees C
deltaHc = 274 j/g
deltaHv = 1621 j/g
Cp (s) = 1.72 J/g degrees C
Cp (l) = 2.83 J/g degrees C
Cp (g) = 1.59 J/g degrees C
how many kcal would it take to completely vaporize 0.264 kg of acetic acid, originally at -16.4 degrees C? Draw diagram first showing all pertinent info.
We can't draw diagrams on the boards.
q1 = heat to move temperature of solid acetic acid from -16.4 degrees C to its melting point (but it stays a solid).
q1 = mass x specific heat of the solid x (Tf - Ti) where Tf is 14.6 and Ti is -16.4.
q2 = heat to melt acetic acid (change solid to liquid),
q2 = mass x heat of fusion.
q3 = heat to move temperature for liquid acetic acid from 14.6 degrees C to its boiling point.
q3 = mass x specific heat of liquid x (Tf - Ti) where Tf is 167.3 and Ti is 14.6.
q4 = heat to vaporize the liquid to gas.
q4 = mass x heat of vaporization.
Total heat is q1 + q2 + q3 + q4.
The problem asks for kcal; therefore, convert total heat you get in J to calories. 1 cal = 4.18 Joules.
Post your work if you get stuck. Tf is final T and Ti is initial T. Watch the signs, especially the one starting at -16.4 c.
To work out the number of kilocalories (kcal) required to completely vaporize 0.264 kg of acetic acid, we need to calculate the amount of heat energy needed for each phase change.
First, let's draw a diagram illustrating the different phases and relevant information:
```
-------------------------
| | |
| Solid | Liquid |
| State | State |
| | |
-------------------------
|
|
Vapor
State
```
Now, let's break down the process step by step:
1. Heating the solid acetic acid to its melting point:
- Calculate the heat energy needed using the mass (0.264 kg), specific heat capacity of the solid (Cp(s) = 1.72 J/g degrees C), and the temperature difference (mp - initial temperature = 14.6 degrees C - (-16.4 degrees C)).
- Convert the energy from joules to kilocalories (divide by 4184 J to get kcal).
2. Melting the solid acetic acid to liquid acetic acid:
- Calculate the heat energy needed using the mass (0.264 kg), heat of fusion (deltaHf = 274 J/g).
- Convert the energy from joules to kilocalories (divide by 4184 J to get kcal).
3. Heating the liquid acetic acid to its boiling point:
- Calculate the heat energy needed using the mass (0.264 kg), specific heat capacity of the liquid (Cp(l) = 2.83 J/g degrees C), and the temperature difference (bp - mp = 167.3 degrees C - 14.6 degrees C).
- Convert the energy from joules to kilocalories (divide by 4184 J to get kcal).
4. Vaporizing the liquid acetic acid to acetic acid vapor:
- Calculate the heat energy needed using the mass (0.264 kg), heat of vaporization (deltaHv = 1621 J/g).
- Convert the energy from joules to kilocalories (divide by 4184 J to get kcal).
Finally, add up these individual energy values to find the total amount of energy required to completely vaporize the acetic acid.
Note: In all calculations, make sure to use consistent units (grams and degrees Celsius) to ensure accurate results.