thermodynamics quiz

open systems

like an open water bottle - allow transfer of matter and energy

closed systems

like a closed water bottle - do not allow transfer of matter, but do allow transfer of energy

Isolated systems

do not allow transfer of matter nor energy. Bomb calorimeters are isolated systems due to being insulated.

state functions

are variables that define how a system starts from howit ends. We calculate final-initial with state functions

path functions

follow the mechanism, or the path, for a given process

extensive property

a property that depends on the extent or size of a system. eg: volume, mass, moles, energy

intensive properties

a property that defines a system. This is not additive. If you ratio two extensive properties, you get out an intensive property. eg: temp, density, prssure

generally if something leaves the system the sign is

(-)

generally if something enters the system, the sign is

(+)

q & w r negative when

energu leaves the system

q & w r positive when energy

enters the system

∆G is negative =

spontaneous

∆G is positive =

non-spontaneous

∆S is positive =

increasing disorder

∆S is negative

increasing order

∆H is negative =

exothermic

∆H is positive=

endothermic

Heat is

chaotic energy, whereas work is a concerted flow of energy that can be easily controlled/guided

Both heat & work r PATH functions, meaning

the methods you take to heat something, change its volume, etc affect the outcome

1st law, ΔUuniv=

0, so energy is conserved

ΔU =

q + w

U is all the sources of

potential and kinetic energy in a system

calorimetry allows ΔUsys=

- ΔUsurrondings

ΔH =

ΔU + PΔV

in a closed system, v is constant so

ΔU = qv because no PΔV work

In an open system, P is constant so

ΔH = qp

W =

-PΔV = -ΔngRT

For a chemical reaction in which there is a change in # ofgas molecules, it is easy

to determine PΔV work

general equation for enthalpy

H=U+PV

change in enthalpy

ΔH=ΔU+PΔV

q

heat

w

work (energy transfer due to forces like expansion or compression)

ΔG

change in Gibbs free energy (determines spontaneity)

ΔS

change in entropy (disorder or randomness)

ΔH

change in enthalpy (heat at constant pressure)

If products are greater than reactants, energy enters or exits & is ΔU positive/negative

enters, positive

if products are less than reactants, energy enters/exits & is ΔU positive/negative

exits, negative

parts of a bomb calorimeter

whats does igniting the bomb calo0rimeter do

starts the reaction of the sample

the water serves as a ______ _____ in order to measure the temp change

heat sink

the setup needs constant stirring to ensure accurate

ΔT

Bomb calorimeters measure ____ ____ at _____ ______ (ΔU = qV)

heat change, constant volume

bomb calorimeters arent isolated so they arent sufficiently isolated for heat change from ΔT is

completely accurate, they arent completely isolated bc only universe can truly be isolated completely

q=

mC∆T+CΔT. mC∆T is water, C∆T is calorimeter

qsys=

-qsurr

f given multiples (moles or #

items), then convert to PER

____ or PER ____

mole, item

specific heat capacity is ____ proportional to temp

inversely