Level 86
Level 88

#### 93 words 0 ignored

Ready to learn
Ready to review

## Ignore words

Check the boxes below to ignore/unignore words, then click save at the bottom. Ignored words will never appear in any learning session.

**Ignore?**

describe molecular motion of real gases

constant above 0°K, random, straight line unless it collides

low concentration, by random collision

are gases most likely to go towards areas of high concentration or low concentration, why?

less molar mass

do gases with greater molar mass or less molar mass diffuse faster?

what does effusion describe?

the passage of bass into an evacuated container

they have definite volume, and IMF

why can't you use PV=nRT for real gases?

lower

electrons that are closer to the nucleus have a _______ energy

higher molar mass

is a molecule with higher or lower molar mass going to be affected by IMF more.

Higher

Electron affinity tends to become from left to right across a row of the periodic table

Cl₂, more IMF

is O₂ or Cl₂ going to deviate more from an ideal gas? why?

Temperature

? T :: ? collisions :: ? rate of reaction

Heat, q

path function

measuring S

3rd Law of Thermodynamics

Important Units for PV = nRT

P: Pa 1 bar = 1x10^5 Pa

(Ideal)

Dalton's Law

intensive property

a physical property such as boiling point, density, or color that does NOT change when you change the size of an object.

What is one major flaw of Ideal Gases?

there would be no intermolecular interactions and therefore liquids and solids could not exist

compressibility

a measure of how much the volume of matter decreases under pressure

critical point

critical temperature+critical pressure

0

0

supercritical fluid

heating above Tc

(Non-ideal)

Equations of State

Virial Equation of State

polynomial expansions of the compressibility factor and can provide more "theoretically-grounded" equations of state

Van der Waal Equation of State

adjusts V to account for occupied space of e clouds (attractions ONLY!!!)

Law of Corresponding States

two gases have corresponding states if they have the same reduced T and reduced P

corresponding states

two states that have the same reduced V

state functions

What are internal energy changes?

Path Functions

properties that depend on the path taken (ex. W)

Expansion Coefficients (alpha or beta)

measure of the affect of T on V @ constant P

Isothermal Compressibility (k, kappa)

measure of the effect of P on V @ constant T

Inverse Rule

(dP/dT)v = 1/(dT/dP)v

Euler's Chain Rule

(dP/dV)t * (dV/dT)p * (dT/dP)v = -1

[d(dP/dT)/dV]t = [d(dP/dV)/dT]v

Variables in Succession rule

q=0

Adiabatic process

W =0

Isochoric process (constant V)

Heat Capacity, C

a substances response to heat flow

Enthalpy, H

ΔH = ΔU - W

Kirchoff's Law

uses a cycle of reactions and known ΔHf's to determine ΔHrxn's of a specific reaction

Coffee Cup Calorimeter

@constant P

Bomb Calorimeter

@ constant V

Differential Scanning Calorimetry

Heat flux model

Power Compensation Model

tries to keep both at the same temp.

Carnot Engine

reversible hat engine b/c all steps are reversible

Clausius's Inequality

explains engines that don't have perfectly reversible steps

Entropy of mixing

spontaneous process (irreversible w/o outside influence)

ideal gas

a gas in which the particles undergo elastic collisions (when particles collide, there is no loss in the speed of the particles)

size, particles, interactions, reality

ideal gas: the _______of the _______don't matter, _______ are not important, not _______

Density

amount of mass per units volume

mmP/RT

density

Ptotal

ntotalRT/V

ntotalRT/V

Ptotal

number of moles, pressure, gas

total _______ is directly proportional to total _______ regardless of _______

directly

total number of moles is _______ proportional to total pressure regardless of gas

density, molar mass

_______is directly proportional to _______

temperature, velocity

as _______ changes, _______ changes

forces, speed, temperature, pressure,average velocity

_______ become significant when _______, _______, _______and _______ changes

molecular motion, temperature

_______ slows at lower _______

slows

molecular motion slows at _______ temperature

higher, more

the _______the van der waals constant, the _______ intermolecular forces

van der waals, intermolecular forces

the higher the _______ constant, the more _______

van der waals

a modification of the ideal gas law that includes correction terms for molecular size and attractive forces

ideal gas law, molecular size, attractive forces

van der waals: a modification of the _______ that includes correction terms for _______ and _______

critical temperature

temperature above which liquid phase of substance cannot exist (i.e. above this point, no gas can be liquified regardless of pressure)

critical pressure

lowest pressure where it can stay a liquid state at critical temperature

Critical State

a fluid at its critical point

Reduced Pressure

Pr = P/Pc

Reduced Temperature

Tr = T/Tc

Reduced Volume

Vr = V/Vc

Why do real gases show deviations from perfect gases?

Molecules in a real gas interact with one another.

Repulsive

What forces between molecules assist expansion?

When are repulsive forces significant?

When molecules are almost in contact, they're short range interactions.

When are attractive forces ineffective?

When molecules are far apart.

What happens to IM forces when the temperature is low?

The molecules travel with such low mean speeds that they can be captured by one another.

What happens to a sample at low pressures?

When the sample occupies a large volume, the molecules are so far apart the IM forces don't play a significant role. The gas basically behaves ideally (perfectly)

Attractive forces dominate,

Which forces dominate at moderate pressures?

Repulsive forces,

Which forces dominate at high pressures?

Compression Factor (Z) of a Gas

Ratio of a gas's measured molar volume (Vm) to the molar volume of a perfect gas (Vm0)

Z = 1

What is the compression factor for a perfect gas?

Z > 1

What's the value for Z at high pressures?

Z < 1

What's the value for Z at intermediate pressures?

Vapor pressure

Force exerted by vapor particles directly above a liquid

Vander Waals Coefficients

Constants (a) and (b) in the vander waal equation of state.

Constant (a)

Represents the strength of the attractive interactions.

Constant (b)

Represents the strength of repulsive interactions.

Calculations of Excluded Volune

Closest distance of two hard sphere molecules of radius r...

Principle (1) of Van der Waal equation

Perfect gas isotherms are obtained at high temperatures and large molecular volumes.

Principle (1) Explained

At a high temp, RT is so large that the first term in the VDW eqn. >>>>> the 2nd term.

Principle (2) of Van der Waal equation

Liquids and gases coexist when cohesive and dispersing effects are in balance.

Principle 2 Explained

The 1rsr term arises from the KE of molecules and their repulsive interactions.

Principle (3) of Van der Waal equation

The critical constants are related to the Van der Waal coefficients.

Principle 3 explained

Vc = 3b

Principle of Corresponding States

Real gases at the same reduced volume and reduced temperature exert the same reduced pressure.

Under what conditions does the principle of corresponding states work best?

It works best for gases composed of spherical molecules. It fails sometimes for polar/non-spherical molecules.

Z = 1 + [b - (a/RT)] (1/Vm)

Two Expansions for Z based on the Van der Waal equation