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

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In summary, the problem requires determining ΔH, which can be calculated using the equation ΔH = ΔU + VΔP. Since ΔV is negligible, the equation simplifies to ΔH = ΔU + VΔP. The question then asks for clarification on what ΔU and VΔP represent in this equation.
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Homework Statement



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Homework Equations



[itex]h_2 - h_1 = (u_2 + P_2v_2) - (u_1 + P_1v_1)[/itex]

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
 

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

1. What is enthalpy and why is it important?

Enthalpy is a measure of the total energy of a thermodynamic system. It is important because it helps us understand the flow and transfer of energy in a system, which is crucial in many scientific and engineering applications.

2. How is the change in enthalpy calculated?

The change in enthalpy is calculated by finding the difference between the enthalpy of the products and the enthalpy of the reactants in a chemical reaction. It can also be calculated by measuring the heat transferred during a physical or chemical process.

3. What factors can cause a change in enthalpy?

Changes in enthalpy can be caused by changes in temperature, pressure, or the amount of substances present in a system. Chemical reactions, phase changes, and physical processes can also result in a change in enthalpy.

4. How is the change in enthalpy related to the heat of reaction?

The change in enthalpy is directly related to the heat of reaction, which is the amount of heat released or absorbed during a chemical reaction. The change in enthalpy is equal to the heat of reaction when the reaction is carried out at constant pressure.

5. What is the significance of a negative or positive change in enthalpy?

A negative change in enthalpy indicates that the reaction is exothermic, meaning it releases heat to the surroundings. A positive change in enthalpy indicates an endothermic reaction, which absorbs heat from the surroundings. These values can help us understand the nature of a reaction and its potential for energy production or consumption.

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