thermo Flashcards
zeroth law
if 1st object in thermal eq with 2nd object
and the 2nd object is in thermal eq w 3rd object
then 1st and 3rd objects are also in thermal eq
thermal expansion
for length:
deltaL = alpha (L) (delta T)
alpha = coeff
for volume:
delta V = beta (V) (delta T)
types of systems
Isolated - no exchange of energy or matter
closed - exchange of energy not matter
open- exchange energy and matter
State vs process functions
state- path independent
process- path dependent, work, heat
1 Cal (nut) =
1 Cal (nut) = 1000 cal = 4184 J
Heat transfer no medium
Conduction - molecule to molecule
- need touch
- i.e.: finger to stove
Convection - gas fluid over material
Radiation - by e-mag waves
- unlike others can = vacuum
Specific heat q
raise heat go 1g by 1K
for water = 1
heat gained or lost by an object
q = MC deltaT q = heat gained/lost
first law of thermo
change in internal energy of system is equal to the amount of energy transferred as heat minus energy transferred as work
delta U = Q -W
delta U = total change in internal energy
Q = energy transferred INTO system as heat
W = work done BY system
Second Law of thermo
objects in thermal contact but not in thermal equilibrium will exchange energy so that
high temp –> low temp
until thermal eq
Heat gained/lost (for phase change)
q = mL q = amount of heat lost/gained m = mass L = heat of transformation
Shortcuts for first law:
- isothermal process
- adiabatic
- isobaric
- isochoric / isovolumetric
- isothermal process Q = W
- adiabatic: delta U = -W
- isobaric: multiple forms
- isochoric / isovolumetric: delta U = Q
Energy dispersion (second law)
delta S = Qrev / T
change in entropy
Qrev= heat gain/lost in reversible process
T = temp in K
constant volume calorimeter
measure system to surr heat transfer
system = reaction chamber
surr = water
setup can ensure Usystem = -Usurr
constant volume means W = 0 so U = Q
so qsystem = -qsurr
since q= MCAT then
MCAT (system) = MCAT (surr)
q = mL =
n x heat of fusion (kJ/mol)
n = number mol
