1.) Find w rev (in units of J) for the following multi-step compressions(or expa

Question

1.) Find wrev (in units of J) for the following multi-step compressions(or expansions):

Give your answer in Joules with zero decimal places.-- I got 146J but apparently thats wrong?

2.) If a piston expands from a volume of (8.7500x10^0) L to a volume of (1.03x10^1) L against a constant pressure of (2.630x10^0) atm, what is the value of work (w) with respect to the system? Give your answer in Kilojoules.

I got 4.263 x 10^-1 but apparently that's also wrong. I changed L to m^3 and atm to Pa, is that right?

3.) 1.39 moles of sodium metal is added to water in an open beaker. How much work, in kJ, is done if the reaction takes place at 49.71°C? (Give your answer as an absolute value).

I got 3.73, which again is wrong.

Explanation / Answer

There are multiple questions here. i am allowed to answer only 1 at a time. So I will answer question 2 and 3 for you.
2.
Work = - p (Vf-Vi)
    = 2.63 *(10.3-8.75)
     =4.0765 atm L
since 1 atm -L = 101.3 J
work = - 4.0765 * (101.3)
            = -412.9 J
               = - 0.413 KJ

3)
Latent heat of vapourisation of sodium, L = 107 KJ/mol
Q= n*L
   =1.39*107
    = 148.73 KJ
Since reaction occur at constant temperature, change in internal energy = 0
or,
q+ w = 0
w = -q
= -148.73 KJ

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