In chemistry, a phase is a part of matter that is uniform.

There are 4 phases• Solid• Liquid• Gas• Plasma

Deposition

Sublimation

Melting

Freezing

Evaporation

Condensation

Molecular Forces

Ionic and covalent bonds are called (within molecules)

– between molecules – also called forces –

Intermolecular forces are than intramolecular forces, so they can be broken first.

intramolecular

Intermolecular

WEAKVan der Waals

always weaker

Dipole-dipole interactions – between ___ _______ covalent molecules

Hydrogen Bonding – between ___ in one molecule with ___, ___, or ___, in another molecule. It is an unusually __________ bond and a special type of dipole-dipole interactions.

Dipole-induced dipole interactions – between ___ _______ and ___ _________ covalent molecules

London’s Dispersion Forces – between ___ ____________ covalent molecules

polar

polar

nonpolar

HFN O

2

2

1 1 nonpolar

strong

The stronger the types of bonds, the more likely it will

be a solid, the weaker the types of bonds, the more

likely it will be a gas.

But before we can discuss those, we need to define a

phase equilibrium

The state in which a chemical process and the reverse chemical process occur at the same rate

Boiling Point• The temperature and pressure at which a

liquid and a gas are in equilibrium Melting Point

• The temperature and pressure at which a solid becomes a liquid.

Freezing Point• The temperature and pressure at which a

liquid substance freezes

Triple point• The temperature and pressure conditions at

which the solid, liquid and gaseous phases of a substance coexist at equilibrium

Critical Point• The temperature and pressure at which the

gas and liquid states of a substance become identical and form one phase – the supercritical fluid

As a result, each substance has a different phase diagram

A graph of the relationship between the physical state of a substance and the temperature and pressure of the substance

Phase Diagram of Water

From pg 404 The triple point of carbon dioxide is at

-56.7 C and 518 kPa. The critical point is at 31.3 C and 7.38 x 103 kPa. Vapor pressure above solid carbon dioxide is 101.3 kPa at -78.5 C. Solid carbon dioxide is denser than liquid carbon dioxide. Sketch the phase diagram.

Phase Diagram of CO2

Let’s do them on the boards.

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