Kinetic energy of gasses(feels incomplete) Flashcards
What are the macroscopic properties of matter?
Mass, density, pressure, temperature, volume, phase
What do models show in kinetic theory?
How microscopic properties determine macroscopic properties
What is an ideal gas?
Simplest gas model with infinitely small point particles, no intermolecular forces between moelcules
What are the state variables of a substance?
Pressure (p), volume (V), temperature (T), amount (m or n)
What is the ideal gas equation with moles?
p V = n R T. (R= ideal gas constant)
What is the ideal gas equation with molecules?
p V = N k T
How is number of moles (n) calculated?
n = m_total / M or n = N / N_A
What is molar mass (M)?
Mass per mole of a substance
How is density (ρ) expressed for an ideal gas?
ρ = p M / R T
What equation applies for constant moles?
p1 V1 / T1 = p2 V2 / T2
What is an equation of state?
Relation between p, V, T for a substance in equilibrium
What happens to pressure if volume decreases (T, n constant)?
Pressure increases
What is the average translational kinetic energy of a gas molecule?
K = (3/2) k T
What is the total kinetic energy of 1 mole of gas?
K_tr = (3/2) n R T
What is the rms speed (v_rms) of gas molecules?
v_rms = sqrt(3 R T / M) or sqrt(3 k T / m)
What does the Maxwell-Boltzmann distribution describe?
Distribution of molecular speeds in an ideal gas
What is C_V for monatomic vs diatomic gases and why?
Monatomic: (3/2) R; Diatomic: (5/2) R; each degree of freedom gets (1/2) k T
What does a phase diagram show?
Conditions for phase equilibrium (p vs T)
What is the triple point?
Where solid, liquid, and gas coexist
What is the critical point?
End of vaporization curve, liquid-gas distinction disappears
How does pressure affect water’s melting point?
Increases pressure lowers melting point below 0 degrees C
What is the mass of a single molecule?
m = M / N_A
What is the relation between p and T if V is constant?
p ∝ T (p V = n R T)
How does pressure behave in small gas volumes (up to 100 m)?
Change is very small, so pressure is taken as constant everywhere
How does pressure change with height in the atmosphere?
Pressure decreases as elevation (height above sea level) increases
How does pressure change with height in a liquid?
Pressure changes with height; p2 + ρ g y2 = p1 + ρ g y1
What is the equation for gas pressure as a function of height?
p = p0 e^(-g M y / R T), where p0 is pressure at height 0
What is a formula for k(boltzman constant) in pV = NkT
k = R/Na
convert g/mol to kg/mol
x 10^-3
in what unit is molar mass
kg/mol
on a maxbell boltzmann speed distribution curve what does Vmp and Vrms stand for and what is the area under the whole graph.
Vmp - most probable speed
Vrms - average speed of particles
Area = 1
mean free time
(formula will be provided) average time between collisions
mean free path
(formula will be provided) average distance between collisions
when working with moles will you use k or R
R
How is molar heat capacity related to the ideal gas constant?
C_p − C_v = R
Internal energy
energy stored in a substance as kinetic and potential energy of its molecules. also determines the phase.
U_0 mean in a potential energy curve
amount of energy needed for the atom to escape the attraction of its partner
r_0 mean in a potential energy curve
equilibrium spacing - the attractive and repulsive forces cancel(net force = zero). the two atoms have minimum potential energy
what is a critical point
changes smoothly above this point rather than undergoing a phase change
fusion
solid + liquid
vapor
vapor + liquid
sublimation
solid+ vapor
