Kinetic Energy Attractions vs. Unit 12: States of Matter GAS LIQUID SOLID main difference between phases is… the distance between particles… …which depends on two competing factors: Kinetic Energy (Kinetic Energy of the particles) Attractions (Attractions between particles, IMAFs) vs.

Kinetic-Molecular Theory (of Gases) 5 Parts of KMT have negligible volume (are tiny) compared to the great distance between have negligible attractions because they are so far apart 10 x

are in constant, random motion 5 Parts of KMT are in constant, random motion Elastic (like marbles colliding) have perfectly elastic collisions (transfer KE without loss, like billiard balls) as opposed to Inelastic (like clay balls colliding)

K = oC + 273.15 no KE 5 Parts of KMT ↑Temp as ↑KEavg 0 K absolute zero average KE (which already considers mass) is directly proportional to temperature ↑Temp as ↑KEavg 373 K 273 K K = oC + 273.15 no KE 0 K absolute zero –273oC.15 –459.67oF

Working against attractive forces SOLID LIQUID GAS video clip low KE, vibrates higher KE, flows highest KE, expands VLC – media file (Changes of State) compressible

Phase Changes

liquid solid + energy liquid solid + energy freezing: l to s (lose KE) liquid solid + energy Forces of attraction between molecules cause them to get closer, then vibrate about fixed positions and form a solid. liquid solid + energy melting: s to l (gain KE)

energy + liquid gas vaporization: evaporation: l to g at surface boiling: l to g beneath surface

gas liquid + energy condensation: g to l (lose KE) warm water vapor in air ice cubes cold water inside glass condensed drops outside glass Is water in glass cooler or warmer ?

sublimation: s to g (gain KE) energy + solid gas deposition: g to s (lose KE) solid gas + energy

GAS SOLID LIQUID Phase Changes condensation sublimation deposition Energy Absorbed Energy Released GAS condensation sublimation deposition vaporization Video – Changes of State melting SOLID LIQUID freezing

1) According to the kinetic molecular theory, gas particles... Quick Quiz! 1) According to the kinetic molecular theory, gas particles... A) are attracted to each other. B) are in constant random motion. C) have the same kinetic energy . D) have a significant volume. 12

Quick Quiz. 2) The average kinetic energy of the particles in a substance is directly proportional to the A) molar mass B) density C) temperature D) size 13

A) attract each other significantly B) are spaced relatively far apart Quick Quiz. 3) Compared to liquids and solids, gases are easily compressed because the particles in a gas… A) attract each other significantly B) are spaced relatively far apart C) are extremely small D) move in constant, random motion 14

Quick Quiz. 4) What is –88oC in Kelvin temperature? A) 185 K B) 361 K C) –361 K D) 273 K K = oC + 273 K = –88 + 273 15

Quick Quiz. 5) Put a cup of water on a table. The process that occurs is… A) evaporation. B) condensation. C) BOTH A and B D) NONE of the above