# Enthelpy change for different processes.

• olap001
In summary, the conversation discusses the calculation of enthalpy change for different types of processes such as constant volume, isothermal, and adiabatic. The speaker mentions that they have not seen any examples for calculating enthalpy change in these processes, but believes it is relevant and asks for assistance. The other speaker provides three questions that demonstrate the relevance of these calculations.
olap001
We know that the enthalpy change for a constant pressure process dh=cpdt.

Can we calculate the enthalpy change for a constant volume process, an isothermal process and an adiabatic process. If so how relevant are these calculations?

Ive been trying to work this out all week and I've never seen any examples asking for the enthalpy change for any other processes other than a constant pressure process

Your help will be greatly appreciated

These are 3 valid (good) questions, and the calculations are (very) relevant:
1. a solid that is heated can be considered to be a constant volume process.
2. a chemical reaction proceeding "at constant T" gives the heat of reaction.
3. the throttling process is an adiabatic process with many applications.

## 1. What is enthalpy change?

Enthalpy change is a measure of the amount of energy released or absorbed during a chemical reaction or physical process.

## 2. Why is enthalpy change important?

Enthalpy change is important because it helps us understand the energy changes that occur during a process. This can provide valuable information for designing and optimizing processes, as well as predicting the direction of a reaction.

## 3. How is enthalpy change calculated?

Enthalpy change is calculated by taking the difference between the enthalpy of the products and the enthalpy of the reactants. This can be determined experimentally or using thermodynamic data.

## 4. What factors can affect enthalpy change?

The factors that can affect enthalpy change include the nature and amount of reactants and products, temperature, pressure, and the presence of a catalyst.

## 5. How does enthalpy change differ for exothermic and endothermic processes?

In an exothermic process, the enthalpy change is negative because energy is released from the system. In an endothermic process, the enthalpy change is positive because energy is absorbed by the system.

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