States of Matter
A Matter of Kinetic Energy
Types of States of Matter
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Solid
Liquid
Gas
Plasma
BEC, or Bose-Einstein Condensate
– Zero State of Matter
– Most Dense
Changes of State
Kinetic Energy (kelvins & paschals)
chemwiki.ucdavis.edu/Physical_Chemistry/Physical_Properties_
of_Matter/Supercritical_Fluids
• Supercritical fluids are useful in science today
– extraction of floral fragrance
– the process of creating decaffeinated coffee
– food science and functional food ingredients
– pharmaceuticals, cosmetics, polymers, powders,
bio- and functional materials
– nano-systems, natural products, biotechnology,
fossil & biofuels, microelectronics & environment
(Bottini 133).
www.engineeringtoolbox.com/vapor-steam-d_609
• Superheated Vapor
• When the temperature is higher than the boiling
point @ a given pressure.
• Vapor cannot exist in contact with the fluid, nor
contain fluid particles.
• Increase in pressure or decrease in temperature
will not, within limits, condensate out liquid
particles in the vapor.
• Highly superheated vapors are gases that
approximately follow the general gas law.
Critical Temp & Pressure
• Critical Temperature
– The temperature at which only gas exists,
regardless of its pressure
• Critical Pressure
– The lowest pressure at which liquids exist at
critical temperature
• Critical Point
– The intersection of critical temperature & pressure
CO2 Phase Diagram
Kinetic-Molecular Theory of Gases
• Ideal gas = hypothetical gas perfectly aligns
with all kinetic-molecular theory assumptions
• Five Assumptions
– Distance between molecules dwarfs actual size
– All collisions are perfectly elastic
– Particles are in continuous, rapid, random motion
– Particles have NO attraction to each other
– Temperature = average kinetic energy of particles
Nature of Gases
• Ideal vs. Real
– Real approaches ideal @ low pressure/ high temp
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Expansion – molecules fill entire space
Fluidity – no intermolecular attractions
Density - ~ 10-3 of liquid or solid state
Compressibility – 100X more than liquids
Diffusion & Effusion
– Diffusion: Spontaneous mixing via random motion
– Effusion: Passing through tiny opening
Properties of Liquids
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LEAST common state of matter in universe
Fluids (as are gases)
Lower kinetic energy than gases
Interactive forces keep molecules connected
– Dipole-dipole forces
• Equal but opposite charges separated by short distance
– London dispersion forces
• Spontaneous creation of dipoles (polar & nonpolar)
– Hydrogen bonding (electronegativity)
Properties of Liquids, continued
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Density: 100x > gases; 10% < solids
Compressibility: @ 103 atm., volume ~ 4%
Diffusion: present, but slower than in gases
Surface tension: high intermolecular attraction
Capillary action: attraction between surfaces
of liquid and a solid
• Vaporization: evaporation & boiling  gas
Nature of Solids
• Interparticle attractions stronger than others
• Two types of solids
– Crystalline (orderly arrangement)
– Amorphous (random arrangement)
• supercooled liquids: have liquid properties even if look
solid (like glass and plastics)
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Shape & Volume: Definite
Melting Point: Definite
Density & Incompressibility: High
Diffusion: Low rate (10-6 less than others)
Crystalline Solids
• Ionic
• Alkali & alkaline earth with halogens & Group 16
• Hard, brittle, high melting points, good insulators
• Covalent network
• Cx (diamonds), (SiO2)x quartz, (SiC)x
• Very hard and brittle, high MP, semi- or nonconductors
• Covalent molecular (nonpolar & polar)
• H2, CH4, C6H6: only weak London dispersion forces
• H2O & NH3,: stronger forces but weaker than covalent
• Soft, low MP, low BP, good insulators