PChem U1

Mixture

Contains two or more pure substances; can be homogeneous or heterogeneous

Homogeneous

In chemistry, homogeneous refers to a substance or mixture that has a uniform composition throughout. This means that any sample taken from a homogeneous mixture will have the same characteristics and properties, regardless of where it is taken from..

Heterogeneous

In chemistry, "heterogeneous" refers to a mixture that is composed of different constituents or dissimilar components. This means that the composition of a heterogeneous mixture is non-uniform, varying from one location to another within the mixture.

Extensive Properties

Properties that depend on the amount of substance (mass, length)

Intensive Properties

Properties that do not depend on the amount of substance (such as boiling point, density).

Phase Change

The transition of a substance from one state of matter to another, such as solid to liquid or liquid to gas, often involving energy changes.

Kelvin Equation

K = C + 273.15

Sublimation

The process by which a solid turns directly into a gas without passing through the liquid phase

Deposition

The process by which a gas turns directly into a solid

Condensation

Gas —> Liquid

Vaporization

Liquid —> Gas

Melting

Solid —> Liquid

Freezing

Liquid —> Solid

Viscosity

the resistance of a fluid to flow or change shape

Critical Point

the point at which two phases of a substance initially become indistinguishable from one another. The critical point is the end point of a phase equilibrium curve, defined by a critical pressure T_p and critical temperature P_c. At this point, there is no phase boundary.

Supercritical Fluid

Substance that exhibits properties of both liquids and gases

Triple Point

the unique temperature and pressure at which a substance can exist simultaneously in solid, liquid, and gas phases in thermodynamic equilibrium.

atm

atmospheric pressure

Volatile

easily evaporated

more evaporation =

= more pressure and lower boiling point

Volatility

A measure of how easily a liquid changes to a gas (evaporation)

Work =

= Force x Distance

Unit for energy

joules

Unit for pressure

Pascals (Pa)

760 mm Hg (Mercury) =

= 1 atm

Boiling of a liquid occurs when

occurs when its vapor pressure equals the atmospheric pressure

kilojoules (kJ) to joules (J)

1 kJ = 1000 J

kilocalories (kcals) to kilojoules (kJ)

1 kcal = 4.184 kJ

calories to joules

1 cal = 4.184 J

Pressure =

= Force/Area

Temperature is a measurement of

average kinetic energy per particle

Latent heat

Energy released or absorbed during a phase transition due to changes in the potential energy of the system.

Pressure is the

number of collisions

Ideal gas law

PV = k_bNT

R =

= 0.0821 L x atm/(K x mol)

k_b

= Boltzmann constant

∝

direct proportionality

Kinetic energy is due to particle ____

motion

potential energy is due to particle ____

interactions

As particles move away from each other, potential energy ______

INCREASES

As particles move closer to each other, potential energy ______

DECREASES

KE =

= ½ mv²

Ionic Bond

Transfer of valence electrons (metals and nonmetals)

Covalent Bond

Sharing of electrons (nonmetals)

ions

charged particles

cations

positively charged ions

anions

negatively charged ions

Avogadro’s Number

6.022 × 10²³ particles

Molar mass

mass of one mole of particles of any substance (g/mol)

mass of a volume of a liquid

M = V x d (density)

Consentration

Amount of a substance per unit volume of a mixture.

Elementary substance

composed of identical particles made of free or bonded atoms of the same type

Chemical compound

composed of identical particles made of bonded atoms of two or more different types

Molecular compound (covalent)

They are made up of molecules

Ionic compound

made up of ions arranged in lattice networks (no molecules)

Density =

Mass/Volume

Ions

When # of protons does NOT equal # of electrons

Isotopes

Same # of protons, but different # of neutrons