thermodynamics - unit 4 exam 1

what can move in an open system

energy and matter

what can move in a closed system

energy only

what can move in an isolated system

nothing

si unit for energy

joule ( J )

hours to seconds

ex: 1 hr = 3600

state function

depends on initial and final state

path function

depends on how the process happens

ex of state functions

e, h, s, t, p, v

ex of path functions

heat ( q ) and work ( w )

heat absorbed by system ( q ) sign

positive

heat released by system ( q ) sign

negative

work done ON system ( w ) sign

positive

work done by system ( w ) sign

negative

heat

random energy transfer ( temperature difference )

work

organized energy transfer ( force/volume change )

exothermic reaction Δh sign

negative

endothermic reaction ΔH sign

positive

exothermic

heat released

endothermic

heat absorbed

entropy ( ΔS )

measure of disorder

entropy increases

more disorder, more particles, gas formation

entropy decrease

more order, freezing, condensing

sign of ΔS for solid → liquid → gas

positive

sign of ΔS for gas → liquid → solid

negative

gibbs free energy ( ΔG )

the usable energy in a system available to do work at constant temperature and pressure

ΔG < 0

spontaneous

ΔG > 0

not spontaneous

negative ΔH and positive ΔS

always spontaneous

positive ΔH and negative ΔS

never spontaneous

negative ΔH & ΔS

temp dependent

positive ΔH & ΔS

temp dependent

equation for internal energy

ΔU = q + w

ΔU

change in total energy of a system

work equation

w + -PΔV

sign of w when volume increases

negative

sign of w when volume decreases

positive

equation for heat transfer

q = mcΔt

c

specific heat

slow specific heat

larger temp change ( ΔT )

high specific heat

smaller temp change ( ΔT )

calorimetry

heat loss = heat gained

absorbs heat in a calorimeter

water ( and sometimes calorimeter )

total heat in calorimetry

water + calorimeter

system type in a bomb calorimeter

closed

reaction type in bomb calorimeter

combustion

water temperature in a bomb calorimeter

increases

energy need to melt/freeze uses

heat of fusion

energy needed to vaporize/condense uses

heat of vaporization

formula for phase change energy

g = mΔh

ΔH represents on diagrams

difference between reactants and products

products lower than reactants

exothermic

products higher than reactants

endothermic

work done on the system

positive

entropy when gas → liquid

decreases

expansion on system energy

loses energy