CH NOTES States of Matter

Types of Kinetic Energy Kinetic = motion Kinetic Energy: energy an object has – Translation: forward motion – Rotational: spinning motion – Vibrational: vibrating motion

Kinetic Theory All matter consists of tiny particles that are in constant motion. As a basis for this theory, there are 3 fundamental assumptions. They are:

Kinetic Theory: 1.Particles in a gas are small, hard spheres (no volume)

Kinetic Theory 2.Gas particles are in rapid, constant, random motion.

Kinetic Theory 3.Collisions are perfectly elastic (travel in straight lines)

Kinetic Energy -Kinetic Energy is directly proportional to Kelvin temperature.

Kinetic energy vs. Temperature Average temperature doesn’t mean every molecule has the same kinetic energy. -Absolute zero=all motion of particles ceases and has no kinetic energy. K = o C + 273

Kinetic Theory This explains diffusion: tendency of molecules to move to areas of lower concentration until concentration is uniform throughout.

Properties of Gases Expansion: gases don’t have a definite shape so they completely fill any container they are in Fluidity: because there are no forces between the particles in a gas, they slide right by each other (fluid) What is another fluid?

Properties of Gases Low Density: gases are not dense because their particles are so far away from eachother Compressibility: The volume of a gas can be decreased significantly because particles are far away from each other. (think of air pressure in tires)

Properties of Gases Diffusion and Effusion: –Gases spread out and mix with one another without being stirred. –Diffusion: spontaneous mixing of two gases caused by random motion –Effusion: when gas particles pass through a tiny opening

Gas Pressure -Gas pressure is caused by collisions of molecules -Empty space with no particles is a vacuum.

PRESSURE Is defined as: Force/unit area of a surface Has the equation: P=F/A Uses the following units:

UnitSymbolConversion Factor Millimeters of mercury Mm HgPressure that supports 1 mm of Hg in a barometer AtmosphereAtm760 mm Hg 1.01 x 10 5 Pa PascalPa1N/m 2 Torr 1 mm Hg

Pressure -Barometer measures atmospheric pressure. 1atm = 760 mmHg = 760 torr = 101.3kPa – (Atm =atmospheres kPa = kilopascal)

Converting pressure 1. Convert 450 kPa to: a. mm Hgb. atm 2. Convert 2.5 atm to: a. kPab. mm Hg 1atm = 760 mmHg = 760 torr = 101.3kPa

Answers 1a. 450 kPa | 760 mmHg = 3376 mmHg | kPa 1b 450 kPa | 1 atm = 4.44 atm | kPa 2a. 253kPa2b. 1900mmHg

Ch The Nature of Liquids

Gases and Liquids are Fluid

Atoms and Mc’s in a liquid move in a random pattern relative to one another bc the intermolecular forces are too weak to hold the atom and mc’s in a solid form.

Vapor Pressure: pressure exerted by mc’s that have evaporated from liquid. – Increase temperature=increase kinetic energy=increase vapor pressure

Dynamic equilibrium: occurs when vapor pressure no longer fluctuates (changes). Rate of evaporation = rate of condensation

Boiling Point: When Vapor Pressure = Atmospheric Pressure Make things boil by: – Increase temperature – Lower atmospheric pressure

Boiling point is lower in the mountains Normal Boiling Point: temperature substance boils at

Vapor Pressure and Boiling Point Which compound is: 1.Most volatile? 2.Strongest IMF (intermolecular forces) 3.Highest b.p.?

13.4 Phase Changes

Phase diagram

Phase Diagram

Phase Change Diagram