Hess's Law Flashcards
What does Hess’s law state?
The enthalpy change for a chemical reaction is the same, whatever route is taken from reactants to products essentially the law of Conservation of Energy
onlu depends on initial and final states
What is the enthalpy of formation?
The enthalpy change when one mole compoud is formed from its constituent elements under stndard conditons, all reactants and products being in their standard states
What is the equation for Hess’s law?
What is the difference when using a thermochemical cycles using enthalpy changes of combustion?
reactants often do not react directly to form the compound we are interested in
What is the enthalpy change of combustion?
- ΔCHθ
- enthalpy change when one mole of a substance is completely burnt in oxygen under standard conditions
How do you work out the enthalpy of combustion, using the enthalpy of combustion data?
where the intermediates are the products of combustion
How enthalpy of formation be worked out from enthalpy of combustion>
- if all products will readily burn
- can be put into an ethalpy of combustion cycle
