Unit 3 Flashcards
4 physical properties of gases
Highly compressible
Infinity miscible
(Infinity form a homogeneous mixture)
Thermally expandable
Low density
Why does a gas exert pressure on its environment
Because the molecules are in constant motion
Pressure formula and what is it measured in
P= Force/area
Measured in N/m^2 = 1 Pa
What is boyles law and formula
At constant temp (and moles) pressure is inversely proportional to volume
P1V1 = P2V2
What is Charles’s law and formula
At constant pressure, volume is directly proportional to temp
V1/T1 = V2/T2
What is avagadro’s law and formula
At constant temp and pressure, volume is directly proportional to the number of moles
V1/n1 = V2/n2
Small n equation
n = m/M
Gas density formula
d = m/V
Total pressure formula
Pt = Pa + Pb + Pc
Mole fraction formula
Xa = na/n total
What is the mole fraction also equal to
Pa/P Total
Do gas particles have kinetic and potential energy
And why
Only kinetic
Particles are in continuous random motion and have no inter particle forces
Do gas particles have attraction or repulsion
No
Gases are made up of particles with no defined _____
And why
Volume
Particle size is so small compared to the distance separating them so it’s negligible
Why does the total energy remain CONSTANT
Collisions are elastic
When is the average kinetic energy the same, regardless of the gas
When the temp is the same
Formula for kinetic energy of one particle of gas
1/2 mu ^2
Average kinetic energy for one mole of particles formula
K = (Na)(1/2)mu^-2
Average kinetic energy with respect to RT
k = (3/2) RT
What is Urms and what’s the formula for it
Root mean speed
Urms = sqrt (3RT/M)
M is in kg/mol
Do gases have high or low Urms
High (moving faster)
What is diffusion
Process by which a substance mixes with one or more substances following the movement of particles
What is compression factor
And formula
Ratio of the molar volume of a gas to the molar volume of an ideal gas at the same temp and pressure
cf = PV/nRT
Particles in a REAL gas experience _____ inter particle attraction
Weak
Particles in a REAL gas occupy a ___ volume
Finite
What equation shows how real gases behave
P = nRT/V-nb - a(n/V)^2
nb = correction to volume
(n/V)^2 = correction to pressure
When is ideal gas behaviour observed
At low pressure and high temp
The change in states between solids and liquids is due to a modification in _____ ____
And explain
Intermolecular forces
The energy supplied is used to overcome the imf until the molecules can free themsevles and move form one phase to another
What is a hydrogen bond
Hydrogen bonds to NOF
The stronger the imf, the higher the ___ and ___
Mp
Bp
What is the energy required to overcome a hydrogen bond between
10-40 kJ/mol
London dispersion creates ____________\
An instantaneous intermolecular attraction that is short lived and weak
How much bigger does the M value have to be when looking at mp
Three times bigger
How does size affect mp
Biggest np means most polarizable means highest IMF means highest BP
What is surface tension
The resistance of a liquid to increase in surface area
The higher the surface tension the higher the _____
IMF
What is capillarity
Refers to the spontaneous rising or descent of a liquid in a capillary tube
What is wetting
Ability of a liquid to maintain contact with a surface
What do capillarity and wetting depend on
Cohesive and adhesive forces
What are cohesive forces
IMF between molecules of a liquid
What are adhesive forces
Forces of attraction between molecules of the liquid and the particles present on the surface of the tube
What is the only liquid that chases a convex meniscus
Mercury
When does a concave mensisucs happen
Adhesive > cohesive
When does a convex mensisus form
cohesive > adhesive
What does capillary attraction look like
Tube in bowl of water has water HIGHER than bowl and mensisucs is concave
What does capillary repulsion look like
Tube in bowl of water has water LOWER than bowl and mensisucs is convex
What is viscosity
Resistance of a liquid to flow
High viscosity means high _____
IMF
Are long chain hydrocarbons polar or np
Np
What is vapour pressure of liquids
Gfa
