Enthalpy

[505968894]

What is an easier definition of Hess's law?

[Jackson Crist 1G]

Hess' law just means that you can add the enthalpies of multiple reactions together in order to calculate the enthalpy for the overall reaction you are solving for. And the reason you are able to do this is because enthalpy is a state function (the path/method to the current state or old state or whatever does not matter, only the values at those states).

[Tucker Gruber 2G]

Adding onto what Jackson said, Hess's law allows you to take a reaction that you know the enthalpy of, manipulate it (by reversing it or multiplying it by a constant), and find the enthalpy of that new reaction (reversing the reaction changes the sign of the enthalpy, and multiplying the reaction by a constant multiplies the enthalpy by that same constant). After that, you can use that new reaction and that new enthalpy as part of the overall reaction you are solving for (by adding it to other reactions, like Jackson described). Hope that helps!

[Kelly Tang 1B]

Hess's Law is a way for you to see how enthalpies of each step of a reaction (steps refer to the multiple equations to create a final one) can factor into the total enthalpy. If you need to manipulate it in order to make certain unwanted reactants/products cancel out, then you can do so by multiplying by the necessary constant or taking the inverse of the provided enthalpy. The total enthalpy of the final reaction would just be the sum of the manipulated ones.

[Anabelle Pham 2C]

It basically means that you can find the overall change in enthalpy in a reaction by adding up the change in enthalpies for each step. You can do this because it is a state function; so, the path to get it does not matter.

[Shiraz Becker 2A]

Enthalpy changes are additive, so you can add up all of the delta Hs for each step of a multistep reaction. The ending number will be the net (or overall) enthalpy change for the entire reaction.

[Grace Strottman 2B]

Hess's Law just tells you that the overall energy change is equal to the sum of the individual reactions that make up the larger one.