chemistry-thermodynamics

Created by

Bethany 123

Cards (31)

what is an open system
where the system is able to exchange both matter and energy with it surroundings for example a pan without a lid
what is a closed system
a system which only has the ability to exchange only energy with its surroundings for example a pan with a lid on it
what is a isolated system
a system that wont exchange either matter or energy with its surroundings an example is a thermos flask
what is the definition of exothermic
heat is released resulting in enthalpy being negative for example the combustion of fuel
what is the deffinition of endothermic
heat is absorbed resulting in enthalpy being positive an example is decomposition of calcium carbonate
what is the equation for gibbs free energy
change in enthalpy -(temperature x change in entropy)
what happens if delta G is less than zero
the reaction will proceed spontaneously in the forward direction where more products are fromed
what happens is delta G is greater than zero
the reaction isnt spontaneous in the forward direction and will proceed in the reverse to make more reactants
what happens if delta G is equal to zero
then the system is in a state of equlibrium and the concentrations of both products and reactants will remain constant
what is enthalpy change
the heat energy transferred in a reaction at a constant pressure
^H= sum of products - sum of reactants
what is the equation for calorimetry
q=mcΔT
what is hess's law
the total enthalpy change of a reaction is independent of the route taken
is the breaking of bonds exothermic or endothermic
endothermic
is the making of bonds exo or endo
exothermic
what is the equation for bond entthalpies
bonds broken - bonds formed
what is the first law of thermodynamics
energy cannot be created or destroyed only transferred to different forms of energy
what is the second law of thermodynamics
an isolated system will spontaneously tend towards its equlibrium state
how can enthalpy change be expressed  
^u +p^V
what is the internal energy
the total energy of a system
the sum of all the molecular motion an atom has
includes both inter and intra molecular forces
^u= Uproducts - Ureactants
what is the equation for the ideal monatomic gas
(3/2)nR^T
how is energy transferred
as heat or as work done
^u=q+w
what happens when heat flows into a system
heat is greater than 0 and u increases
work done is less than 0 and u increases
what happens when energy flows out of a system
heat flows out and is less than 0 so u decreases
work done is greater than 0 so u decreases
what drives spontaneity
the relationship between enthalpy and entropy
what is entropy
a measure of energy dispersal throughout a system and its surroundings
what is the equation for entropy
^s= sum of products - sum of reactants
how does volume affect entropy
increasing volume of a gas increases the entropy
how does temperature affect entropy
increasing temperature of a system increases the avaliable energy levels
how does physical state affect entropy
relates to bot volume and temperature effects
what else affects entropy  
the number of partcles present
how do we predict the sign of entropy
if entropy of a system increases delta s is positive
if entropy of a system decreases delta s is negative