How Do You Calculate the Amount of Heat Transferred in Thermodynamics?

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To calculate the amount of heat transferred in thermodynamics, the equation h_2 - h_1 = (u_2 + P_2v_2) - (u_1 + P_1v_1) is used, focusing on changes in enthalpy. The discussion highlights the importance of referencing saturated liquid tables to find enthalpy values when pressure is not available. It is noted that if there is no change in enthalpy between constant temperatures, the overall enthalpy change may be zero. The user expresses confusion about the terms ΔU and VΔP in the context of the equation ΔH = ΔU + VΔP. Seeking clarification on these terms indicates a need for further understanding of the thermodynamic principles involved.
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Homework Statement



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Homework Equations



h_2 - h_1 = (u_2 + P_2v_2) - (u_1 + P_1v_1)

The Attempt at a Solution



I thought I had to look at the charts in the book for saturated liquid, then notice that the temperature is much higher at the given pressure than what was given in the problem. That would tell me for both situations I have a compressed liquid. But the thing is when our pressure isn't listed in the compressed liquid tables, we are supposed to look at the saturated liquid tables under the given temperature to determine an equivalent amount for what we are trying to solve. In this case it would be enthalpy. And this is true for both cases, which would make the enthalpy zero overall as there is no change in enthalpy between constant temperatures. So I must be approaching this wrong. What is another method to solve this problem?
 
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ΔH = ΔU + Δ(PV) = ΔU + VΔP + PΔV

Since ΔV = 0 (it is negligible) this is simply: ΔH = ΔU + VΔP

What is ΔU here? What is VΔP?

AM
 

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