Thermochemistry Flashcards
work
using energy to move things
heat
using energy to change temperature
thermal work
-P (change in V)
First Law of thermo
change in energy= Efinal-Einitial
change in energy=
q + w = heat + -P(change in V)
endothermic
absorbs heat
exothermic
releases heat
enthalpy
heat flow that occurs when thermal work occurs
enthalpy=
change in H = q = change in E + thermal work
enthalpy of a chemical reaction=
Eproducts- Ereactants
finding the enthalpy of reaction given masses
it is proportional to the amount of reactant consumed. if two moles of C react and the enthalpy of the reactions is -120; if one mole of C reacts, the enthalpy of the reaction is -60
heat capacity
the heat required to raise a substance 1 Kelvin
specific heat
= q/mchange in T= heat transferred/(masschange in T); heat capacity of one gram
heat of a solution=
specific heat of the solution * grams solution * change in T
heat of solution vs reaction
the heat of one has the opposite sign of the heat of the other
Hess’s Law
the sum of all of the changes in heat/enthalpies if there are steps to a reaction
why are there lines between states on a heating curve?
that is the energy it takes to change the state and temperature doesn’t change at that time
heat of fusion
energy it takes to melt a solid, NO TEMPERATURE CHANGE
sublimation
from solid to gas
deposition
from gas to solid
heat of vaporization
energy it takes to vaporize a liquid, NO TEMPERATURE# CHANGE
how to find the heat it takes to make something a different state and different temperature
find the specific heat it takes to get to the state change temperature; find the heat of vaporization/heat of fusion for that state; continue to find specific heat to next state change temperature…
heat of formation
energy it takes to form one mole of a compound from it’s elements in J/mol
heat of formation equation
deltaH= sum(moles products *deltaH products) - sum(moles reactants * deltaH reactants)
