First Law of Thermodynamics

Question 1

The First Law of Thermodynamics

Answer 1

ΔE(thermal)=W(work)+Q(heat)

Question 2

Pv graph how do you calculate work? -+0 answers explain

Answer 2

Work is area under Pv Graph between V(i) and V(f)
W > 0 gas compressed energy transferred to gas from environment
W < 0 gas expands energy transferred from gas to environment
W=0 no work done no volume change Isochoric process

Question 3

Calculating work for Isothermal processes

Answer 3

Work = -∫ p dV 
Ideal gass Law p=(n*R*T)/V
n*R*T = constant can be brought out of intergral
-n*R*Tln(V(f)/V(i))
sub back in p*V for n*R*T
-p*Vln(V(f)/V(i))

Question 4

Define
Thermal Energy
Heat
Temperature

Answer 4

Thermal Energy = energy of system due to motion of atoms
Heat = energy transfered between two systems
Temperature = state variable relates to thermal energy per molecule

Question 5

Pressure on a gas

Answer 5

p(gas)=p(atmos)+m(mass)g(gravity)/A(area)

Question 6

adiabatic process

Answer 6

q(heat)=0

this does not mean ΔT = 0

Question 7

Q=mcΔT

Q=nCΔT

Answer 7

Q Heat transfered = massspecific heat capacitychange in temperature

Question 8

Q=+-mL

Phase Changes are characterized by

Answer 8

ΔE(th) but no ΔT
L(f) heat of fusion
L(v) heat of vaporisation

Question 9

Calorimetry Problems

Answer 9

Qnet=Q1+Q2+..=0
Temp change Q=mcΔT
Phase change Q=+-mL
Final temperature between Ti and Tf

Question 10

Conduction

Q/Δt=(kA/L)ΔT

Answer 10

Temperature transferred between adjacent objects

Heat/time=((thermal conductivitysurfacearea)/ length)difference in temp

Question 11

Convection

Answer 11

Flow of material to transfer heat

Question 12

Radiation

Q/Δt=eσA*ΔT^4

Answer 12

Electromagnetic spectrum
e emissivity of substance
Difference in temperature