Find Enthalpy: Step-by-Step Guide to Calculate H

[acoopermilne]

Please HELP!

I am stuck on how to find enthalpy. I have looked through my book front to back, and I have searched the web, and I can't seem to find out how to find enthalpy other the H=Hproduct -Hreactant formula, which doesn't make sense to me either.

 

[physics girl phd]

Your equation finds the change in enthapy in a reaction, which relates to whether the system is exothermic or endothermic (heat is released or required for the reaction to occur.) You should be able to find something about how enthalpy is a state function and therefore relates to the conditions that the materal is at initially and finally, and maybe about what internal energy is in the initial/final materials. Try to "wikipedia" enthalpy and see if that helps you... but of course because this is an online source, verify whatever you find by other sources, maybe find another book at the library and check it out for a few weeks (some texts cover different subjects better than others, after years of schooling, I look up some things in one text, others in another).

 

[Blueshift5]

Hello,

I understand your frustration with trying to find enthalpy. It can be a complex concept to grasp at first, but with some guidance and practice, you will be able to calculate it easily.

First, let me explain what enthalpy is. Enthalpy (H) is a thermodynamic property that represents the total energy of a system. It takes into account both the internal energy (U) and the work (PΔV) done by the system. Enthalpy is often used to measure the heat energy exchanged during a chemical reaction or physical process.

To calculate enthalpy, you are correct in using the formula H = Hproduct - Hreactant. This formula is known as the enthalpy of reaction (ΔH) and represents the change in enthalpy during a reaction. It is important to note that the enthalpy of reaction is a state function, meaning it only depends on the initial and final states of the system, not the path taken to get there.

Now, let's break down the steps to calculate enthalpy:

1. Determine the reaction equation: The first step is to write out the balanced chemical equation for the reaction you are interested in. This will help you identify the products and reactants that will be used in the next steps.

2. Determine the enthalpy values for the products and reactants: Using reliable sources, such as textbooks or online databases, find the enthalpy values (H) for each product and reactant in the reaction equation. These values are typically given in units of kJ/mol.

3. Calculate the change in enthalpy (ΔH): Using the formula H = Hproduct - Hreactant, subtract the sum of the enthalpy values for the reactants from the sum of the enthalpy values for the products. This will give you the change in enthalpy (ΔH) for the reaction.

4. Consider the sign of ΔH: Depending on the direction of the reaction, the value for ΔH can be positive or negative. A positive ΔH means the reaction is endothermic, meaning heat is absorbed during the reaction. A negative ΔH means the reaction is exothermic, meaning heat is released during the reaction.

5. Apply any appropriate corrections: In some cases, you may need to apply corrections to the enthalpy values to account for factors such as temperature or phase changes. These corrections can