## Midterm winter 2013 question #4

isochoric/isometric:
isothermal:
isobaric:

Priscilla_Covarrubias_HL
Posts: 16
Joined: Sat Sep 24, 2016 3:00 am

### Midterm winter 2013 question #4

For question #4 you are asked to calculate the work from B to C (the process is reversible, isothermal expansion at 3045K). Both volume (L) and pressure (atm) are changing. What equation would you use to calculate work: w=-nRTln(v2/v1) or w=-nRTln(p1/p2)?

Jeffrey_Huang_2K
Posts: 11
Joined: Fri Jul 22, 2016 3:00 am

### Re: Midterm winter 2013 question #4

Because it is an ideal gas, the equations are equivalent due to Boyle's Law. So either one would work and would lead you to the same answer :)

Coco Hailey 2E
Posts: 32
Joined: Fri Sep 25, 2015 3:00 am

### Re: Midterm winter 2013 question #4

Not the same part of Question 4, but still about question 4. In finding the mass of water- where does the equation qwater +qboiling = m_water * C_water * ∆T + m_water * ∆H_vap come from?? I understand how it is related to q = mc∆T but where does the ∆H_vap come from?

Sean_Yue_1E
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### Re: Midterm winter 2013 question #4

@Coco Is the question you're asking about Q3? But I think the Hvap(water)*m(water) is the q(boiling) part of the equation q(water) + q(boiling) = -q(katana) so it's the thermal energy of boiling the water.