At 298K and 1 bar pressure, the density of water is 0.9970g/cm3, and Cp,m = 75.3 J/K

  • #1
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Homework Statement



At 298K and 1 bar pressure, the density of water is 0.9970g/cm3, and Cp,m = 75.3 J/K moL. The change in volume with temperature is given by dV=V(initial)ßdT where ß, the coefficient of thermal expansion is 2.07*10^-4 K^-1 . If the temperature of 250 g of water is increased by 38.0K, calculate w,q,dH,dU



Homework Equations



dV=V(initial)ßdT
dH = qp (heat at constant P) = u + w = u + PV
dU= q + w

The Attempt at a Solution


The answer should be w=-0.197J, q=39700J, dH=39700J, dU= 39700J but I have no idea how to solve this problem. I don't even know where to start...I am completely lost. Please help
 
  • #2
The unit conversions are a little annoying, but the problem is straightforward for the most part. Use the standard Chem 101 formula for heat ##q=mc\Delta T##
Calculate the change in volume and use that to find the expansion work ##P\Delta V## (make sure to get the sign right!). Then you can use these quantities to get ##\Delta U## and ##\Delta H##.
 

Suggested for: At 298K and 1 bar pressure, the density of water is 0.9970g/cm3, and Cp,m = 75.3 J/K

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