3. Thermodynamics Flashcards
What are the 0th vs 1st vs 2nd laws of thermodynamics?
transitive property with thermal equil; heat transfers from hot to cold vs energy cannot be created nor destroyed vs entropy inc spontaneously
Isolated vs closed vs open systems
energy and matter can’t exchange with their surroundings (b/c there are no surroundings) vs energy but not matter can exchange with their surroundings vs energy and matter can exchange with their surroundings
Relationship with deltaU = Q - W. And know the relations in adiabatic, isothermal and isovolumetric/isochoric processes and what they look like on a P-V graph
pos deltaU = inc temp; neg deltaU = dec temp
pos Q = heat flows into system; neg Q = heat flows out of system
pos W = work is done by system => expansion; neg W = work is done on system => compression
Temp of system is constant (looks like a shallow curve on P-V graph) vs no heat exchange occurs (looks hyperbolic or deeper curve on a P-V graph) vs pressure of system is constant vs volume of system is constant
What’s the specific heat capacity? What’s its value for water? What is its formula?
1 cal/gK or 4.184 J/gK
Amount of heat required to raise temp of one mass unit by 1 degree C or 1 K. INVERSE TO DELTAT
c = 3/2nR = Q/deltaT
Formula to use when finding heat energy during a phase change
q = mL
L - in cal/g; heat of transformation or latent heat of substance; represents enthalpy of isothermal process
During a phase change, temp is constant —> deltaT=0 —> not useful when we do q=mcdeltaT
Standard heat of formation formula
DeltaH0 = sumn(deltaHf0) of products - sumn(deltaHf0) of reactants
n = mol DeltaHf0 = standard enthalpy of formation (amount of heat lost or gained in a rxn); usually given
When is deltaH = q?
When there’s constant pressure
Linear vs volume expansion. These concepts relate to thermal expansion
Inc temp causes solid to inc in length, dec temp causes solid to dec in length: deltaL=alphaLdeltaT vs inc temp causes liquid to inc in vol, dec temp causes liquid to dec in vol: deltaV=betaVdeltaT
L=orig length, V=orig vol
Alpha=coefficient of linear expansion
Beta=coefficient of volumetric expansion; beta equals 3alphas for the same material
Heat transfer: conduction vs convection vs radiation
Direct energy transfer via molec collisions vs heat transfer by physical fluid motion vs energy transfer by EM waves
Endergonic vs exergonic
Requires energy, deltaG > 0 vs releases energy, deltaG < 0
Enthalpy of fusion vs enthalpy of vaporization
Enthalpy at solid/liquid change vs liq/gas change
Entropy of univ formula
DeltaS for universe = deltaS for system + deltaS for surroundings > 0
Entropy of system can dec if entropy of surroundings inc by same amount. In an isolated system, entropy always inc
Heat vs thermal equil
Transfer of thermal energy from a hot object (higher energy) to a cold object (lower energy) vs no net heat flows between 2 objects in thermal contact
This all basically reflects 0th law of thermodynamics
How to convert C to F and vice versa?
9/5C + 32 vs 5/9(F-32)
Keep in mind that physical properties of matter (length, solubility and vol) can change based on temp. This relates to thermal expansion
Think about Daniel Fahrenheit and his mercury thermometer thingy
