Enthalpy and Hess's Law

Pressure-Volume Work

mechanical work done when the volume of the system changed in the present of external pressure

w=-PV

Equation for Work of expansion

0

what is the PV work done when volume is constant

Enthalpy

thermodynamic variable that relates directly to energy changes at constant pressure

H = E + PV

Equation for Enthalpy

Change in Enthalpy

change in internal energy plus the product of the pressure, which is constant and the change in volume

heat absorbed or released

What is change in enthalpy equal to at constant pressure

Enthalpy of Reaction

enthalpy change that accompanies a reaction which is equal to the amount of heat gained or lost at constant pressure

Heat capacity

quantity of heat required to changes i ts temp by 1K

Specific Heat Capacity

quantity of heat required to change the temp of 1 gram of the object by 1K

q/t

equation for Heat Capacity (C)

q/mass x t

equation for Specific Heat Capacity (c)

Thermochemical Equation

balanced equation that includes the enthalpy change of the reaction

False

Enthalpy is an Intensive property

True

The enthalpy change for a reaction is equal in magnitude, but opposite in sign

Hess’s Law

states that if a reaction is carried out in a series of steps, the change of H for the overall reaction equals the sum of the enthalpy changes for the individual steps

Standard Enthalpy of Formation

the enthalpy change for the formation equation when all the substances are in their standard state