Chapter 11 : Matter, Energy, and Equilibrium Knowt

study tool for chem chapter 11

The kinetic molecular theory

describes the behavior of matter in terms of particles of motion

Particle size

Gas consists of small particles separated from one another by empty space without attraction or repulsion between them

Particle motion

Gas particles are in random, constant motion until they collide with another particle. These collisions are elastic

elastic

meaning that no kinetic energy is lost, but is transferred between colliding particles

Particle energy

Kinetic energy of a particle depends on the mass and the velocity of the particle

Temperature

the measure of the average kinetic energy of the particles in a sample of matter

As temperature increases, molecular motion increases

Expansion

due to empty space between particles, gases fill and size or shaped container

Compression

Gas particles can be squeezed closer together because of the empty space between them

Gases are the only compressible state of matter

Fluidity

Due to the weak attractive forces, gases have the ability to flow, making them fluids (liquids are also fluids)

What state of matter is the least dense?

Gases

Diffusion

the movement of one material through another

Effusion

when gas escapes through a tiny opening

Liquids (medium density)

Can only exist within a narrow temperature and pressure range

these are the LEAST common state of matter

Description of a Liquid

1. No defined shape

2. Particles are in constant motion

3. Particles are closer and lower in energy than gas particles

4. Attractive forces of liquids are stronger than gases

5. Liquids are more orderly than gases

What states of matter are fluids?

Gases and liquids are fluids, since they can flow and diffuse

Diffusion Rate in Liquids vs. Gases

liquids diffuse slower than gases, even at the same temperature

Diffusion rate does increase with temperature, but liquids are still slower than gases

Viscoscity

the measure of resistance to flow

What is viscosity determined by?

the type of intermolecular forces, size of the particles, as well as shape of the particles.

Surface Tension

the energy required to increase the surface area of a liquid by a given amount

It is also a measure of the inward pull by particles in the interior

What do surfactants do?

Surfactants lower surface tension of water

Cohesion

the force of attraction between identical molecules

Adhesion

the force of attraction between different molecules

Capillary Action

upward movement of liquid into a narrow cylinder (known as a capillary tube)

When is something dissolved?

Something is ONLY dissolved when one physical state is observed

What affects the rate of diffusion

Temperature, State of Matter, Particle Size/Mass and Pressure

Boiling and Evaporation

Boiling occurs throughout the entire liquid Evaporation occurs only at the surface

Where does Evaporation occur?

occurs only at the surface of the liquid and can happen at any temperature

Description of a Solid

1. Particles in a solid vibrate in fixed positions

2. Particles in a solid have strong attractive intermolecular forces

Crystalline Solid

have particles arranged in an orderly, geometric structure

consist of unit cells

Amorphous Solid

the particles are not arranged in regular, repeating patterns

does NOT contain crystals

unit cells

the smallest arrangement of atoms with the same symmetry as the whole

Properties of Crystalline Solids

Particles arranged in a repeating, orderly pattern

Have a definite melting point

Amorphous Solids

Particles arranged randomly with no pattern

No definite melting point

Amorphous and Crystalline Similarity

They both have a defined shape and volume

This means they are NOT fluid since everything is held in fixed positions

Density of Solid (most dense)

Most solids are more dense than liquids.

The only exception is water, where solid ice is less dense than liquid water.

Incompressible and Slow Diffusion Rate of Solids

Solids are incompressible and do not diffuse due to their fixed particles

What property of gas makes them take the shape of their container?

Fluidity

What type of solid does not have a symmetric arrangement?

Amorphous solids

What property of liquids makes them stick to a solid?

Adhesion

Types of Crystalline Solids

Ionic Solid, Covalent Network, Metallic, Covalent Molecular

Ionic Solid (2nd strongest)

positive and negative ions

Ionic Bonds - stronger bonding forces

Hard and brittle with high melting point

Example: NaCl (table salt)

Covalent Network (3rd strongest)

atoms share electrons with neighboring atoms

Covalent bonds - strong bonding forces

Hard and brittle with high melting points

Example- Diamond

Metallic (strongest)

Sea of Electrons - force between atoms of same metal element

High electrical conductivity

Wide range of boiling and melting points

Example: Cu, Fe, Au

Covalent Molecular (weakest)

Covalently bonded molecules held together by Intermolecular Forces

Intermolecular Forces are weaker than ionic and metallic

Soft and volatile, low melting points

Example: Water

Equilibrium

a condition where two opposing changes occur at equal rates in a closed system

Vaporization

Liquid to Gas (includes Evaporation and Boiling)

Condensation

Gas to Liquid

Freezing

Liquid to Solid

Melting

Solid to Liquid

Sublimation

Solid to Vapor Phase

Deposition

Gas to Solid

Exothermic

Heat is released from the system

Ex: Condensation Freezing Deposition

Endothermic

Heat is absorbed by the system

Ex: Vaporization Melting Sublimation

What remains constant during all phase changes?

temperature remains constant

Evaporation

is vaporization only on the surface of the liquid, and occurs in both open and closed containers

process of molecules leaving the surface of non-boiling liquid

Boiling Point (BP)

Temperature where the pressure of a liquid is equal to the atmospheric pressure

Vapor Pressure

pressure exerted by a vapor at a given temperature

What determined Vapor Pressure

The strength of an attraction forces between liquid molecules determines the vapor pressure

Molar Heat of Vaporization

amount of heat required to vaporize one mole of a liquid at its boiling point

Ex: Water- 40.79 kJ/mol

Vapor Pressure Vs. Temp

As temperature increases, vapor pressure increases

Vapor Pressure vs. BP

The lower the vapor pressure, the higher the boiling point

Freezing Point/Melting Point

the temperature at which the solid and liquid phases are in equilibrium at 1 ATM of pressure.

Molar Heat of Fusion

the energy required to melt one mole of a solid at its melting point

Ex: Water - 6.008 kJ/mol

Phase Diagram

graph which indicates the conditions where gas, liquid, and solid phases of a substance exist

Critical Temperature

the highest possible temperature to liquify a gas with any pressure

Critical Pressure

the pressure required to liquify a gas at its critical temperature