States of Matter

What are the 3 states of matter we are concerned about for this class?  Solids  Liquids  Gases

What is a solid?  A state of matter with a definite shape and volume.

What is a liquid?  A state of matter that does not have a definite shape but has a definite volume.

What is a gas?  A state of matter that has no definite shape or volume.

What is the kinetic molecular theory?  Describes the movement of particles.

What does kinetic mean?  To move

How are we going to use the kinetic molecular theory first?  To describe gases.

How small are the particles in a gas?  They are VERY tiny.

How close together are the particles of a gas?  They are as far apart from one another as possible.

What is in between the gas particles?  Nothing, it is empty space.

How often do gas particles move?  They are ALWAYS in motion.

If gas molecules hit one another, what happens?  They bounce off of one another and do not lose any energy.

What do we call that in chemistry?  Elastic or perfectly elastic

What are two factors that affect the movement of a gas particle?  Temperature  Mass

How does temperature affect gas particles?  The hotter the particle, the faster it moves.

How does mass affect movement?  The larger the particle, the slower it moves.

What is the density of a gas?  It is VERY low.

Are gases compressible?  Yes, they are all very compressible.

Are gases expandable?  Yes, gases always take the space of the container.

What is diffusion?  How gases always want to evenly distribute.

What is effusion?  When gas escapes through a tiny opening.

What is pressure?  The force per unit area.

What does that mean?  It is how a balloon holds its shape.

How is the pressure in the air measured?  With a barometer.

What is a manometer?  It measures the pressure of an enclosed gas.

How is pressure measured?  In pascals (Pa), atmospheres (atm), pounds per square inch (psi), mmHg, Torrcelli (torr), or kilopascals (kPa)

How do you convert between units of pressure?  1atm= 101.3kPa  1atm= 760mmHg  1atm= 760torr  1atm= 14.7psi (lb/in 2 )  1 atm= 1.013x10 5 Pa  1 mmHg = 1 torr

Example Problem  Convert 892.8mmHg into atm.

Example Problem  Convert 34psi to torr

What is Daltons law of partial pressure?  That each gas has its own pressure that helps add to the total pressure of the mixture.

What does that mean?  Total pressure= P 1 +P 2 +P 3 …. etc

Example Problem You have a balloon filled with 2.3atm of water vapor, 6.77atm of oxygen, and 4.2atm of hydrogen. What is the total pressure inside the balloon?

Example Problem The total pressure of a mixture of three gases is found to be mmHg. The gases were separated and it was found that there was.23atm of gas 1 and.47atm of gas 2. Gas 3 escaped. What was the pressure of gas 3?

What kinds of forces hold together substances?  Intermolecular forces

What do intermolecular forces hold together?  Either the same types of molecules (water in a drop) or different molecules (graphite to cellulose)

What are the three types of intermolecular forces?  Hydrogen  Dipole-Dipole  Dispersion

What is a dipole-dipole force?  A weak force that holds together polar molecules to one another.  Example: PCl 3, CH 3 Cl

What is a dispersion force?  A weak force that holds non-polar molecules to one another.  Example: H 2, CO 2

What is the strongest type of intermolecular force?  Hydrogen Bonds

What is a hydrogen bond?  It is a bond that forms between molecules that contain hydrogen AND oxygen, nitrogen, or fluorine.

Predict the type of intermolecular force in the following:  HF  N 2  CS 2  CHCl 3 Electronegativity Values: H C N O F Cl S Si Br P- 2.19

How are liquids like gases?  The particles are always in motion  Link Link  They are made of tiny particles  They take the shape of their container

What is the first main difference between a gas and a liquid?  There are intermolecular forces there to hold them together.

How does the density of a liquid compare?  The density is higher than a gas.

Are liquids compressible?  Not really. The particles are too close together.

What is a fluid?  Something that can flow.  Demo Video Clip Demo Video Clip

What states of matter are fluids?  Gases and liquids

What is viscosity?  The resistance of a fluid to flow.

What does that mean?  The intermolecular forces prohibit flowing

What are viscous liquids?  Honey, molasses

As you heat a viscous liquid, what happens?  It loses viscosity.

What is surface tension?  The tendency of a liquid to make its surface area as small as possible.

 Basilisk Running brnryXk brnryXk  Water Striders E6ObU

What is adhesion?  When a liquid “ sticks ” to a different surface.

What does that mean?  Not all liquids are wet (they don ’ t all stick to things)

What is capillary action?  The liquid adheres to a very small area, so it gets drawn up.

What are some examples of capillary action?  Roots of plants  Blood tests  Paper towels

If you compare a liquid and a solid, what are some differences?  Solids have a definite shape.

Why?  Their intermolecular forces are much stronger.

How are solids and liquids alike?  The particles are always in motion, have IM forces and are very small.  Link Link

How do the densities of a solid compare to a liquid?  Density of solids are usually higher.

What are the two types of solids?  Crystalline and amorphous

What is a crystalline solid?  When the molecules are arranged in geometric shapes.

What are some characteristics of crystalline solids?  High melting point  High boiling point  Very strong

What is an amorphous solid?  A solid that does not have a crystalline shape.

What are some examples of amorphous solids?  Plastics  Rubber  Glass

What is needed for any change of state?  Energy

Why is energy needed?  To strengthen or release the intermolecular forces.

How are IM forces related to changes of state?  As you go from gases to liquids to solids, the IM forces get stronger.

What are the phase changes?  Melting, freezing, condensation, evaporation, sublimation, deposition

What phase changes release energy?  Freezing, condensation, deposition

What phase changes absorb energy?  Melting, evaporation, sublimation

Between a liquid and a solid, what happens?  L  S Freezing  S  LMelting

Between a gas and a liquid, what happens?  G  L Condensation  L  GEvaporation

Between a solid and a gas, what happens?  S  G Sublimation  G  SDeposition

Where have I witnessed sublimation?  In the freezer, mothball, dry ice, solid air fresheners.

Where have I witnessed deposition?  Snowflakes, frost

What is vaporization?  When a liquid changes to a gas or a vapor.

What is the difference between vaporization and evaporation?  Evaporation is vaporization that only occurs at the surface of a liquid.

What is boiling?  It is the rapid vaporization of a liquid when it gets to its boiling point. The vapor pressure is equal.

What is vapor pressure?  The pressure that is exerted by a gas evaporating right above the liquid.  Boiling Water with Ice; -EuJU

What needs to be continuously added to a liquid in order for boiling?  Energy

What is a volatile liquid?  One that evaporates very easily due to weak IM forces.

What is a phase diagram?  It is a graph that shows the temperature and pressure of a substance, and the state of matter.

What are the key points on a phase diagram?  Triple point & critical point

What is the triple point?  Where all 3 phases occur simultaneously.  Triple Point Video Triple Point Video

What is the critical point?  The point at which only a supercritical fluid can occur thereafter.  Video: Super Critical Fluid Video: Super Critical Fluid

What happens on the lines?  The phases co-exist at the same time.

Does every substance have its own phase diagram?  Yes.

Phase Diagram