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Pressure/Introductory Thermodynamics

  • Thread starter JamesL
  • Start date
33
0
Not sure what I am doing wrong...

1. Homework Statement
A chemical reaction takes place in a container
of cross-sectional area 100 cm2. As a result of
the reaction, a piston is pushed out through 20
cm against an external pressure of 567 torr.
What is the value for w for this reaction?
(Sign does matter.) Answer in units of J.

2. Homework Equations

w = - (Pressure)(Change in Volume)


3. The Attempt at a Solution

Cross sectional area = 100 cm^2 = .01 m^2
Change is piston distance = 20cm = .2 m

Pressure = 567 torr x 133.322 = 75593.574 Pa


Solution disregarding sign = [75593.574 kg/(m*s^2)][.01 m^2][.2 m]

---> 151.188 J

However this is coming up as incorrect.
 

Answers and Replies

Doc Al
Mentor
44,828
1,084
Looks OK to me. Why are you ignoring the sign when it says "sign does matter"?
 
33
0
Looks OK to me. Why are you ignoring the sign when it says "sign does matter"?
This is why a separate set of eyes is always helpful!
 

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