Topic 1 Stoichiometric Relationships

Compounds

Substances formed by chemically combining two or more elements in fixed ratios, exhibiting unique properties different from their component elements.

Mixtures

Combinations of elements or compounds not chemically bonded, retaining individual properties, with homogeneous mixtures having uniform composition throughout.

Solid state

State of matter with fixed shape and volume, particles held by intermolecular forces, and transitions to gas by sublimation or liquid by melting.

Liquid state

State with fixed volume but takes the shape of the container, transitioning to solid by freezing or gas by boiling/vaporization/evaporation.

Gaseous state

State filling the container, particles widely spaced with negligible forces, transitioning to liquid by condensation or solid by deposition.

Sublimation

solid to gas

Melting

solid to liquid

Freezing

liquid to solid

Boiling/vaporization (volatility)

liquid to gas

Condensation

gas to liquid

Deposition

gas to solid

molar mass

• the mass of one mole of any substance

relative atomic mass

• weighted mean of all the naturally occurring isotopes of the element relative to 1/12 of C-12 atom

empirical formula

• in simplest whole number the ratio of atoms of each element in a substance

molecular formula

• shows the actual number of atoms in a substance

structural formula

• shows the arrangement of atoms and bonds within a molecule

Example of mixture

Air, seawater

Example of compound

Water

Solid state

• fixed shape and volume

• particles held together by intermolecular forces

• particles will vibrate at a fixed point but do not have translational velocity

Liquid state

• fixed volume

• takes up the shape of the container

• held together by intermolecular forces

Gaseous state

• takes the space to completely fill container

• widely spaced particles

• intermolecular forces between particles are negligible

• pressure is due to gaseous particles colliding with the walls of the container

Avogadro's Law

V = constant (k) x n
- Equal volumes of gases at the same temperature and pressure contain equal numbers of particles
- Volume is directly proportional to the number of moles

Molar volume

The volume occupied by one mole of any gas
NOTE: must be the same for ALL gases when under the same conditions of temp and pressure (avogadros law)

what makes an ideal gas (KMT)

1. The volume of the gas particles is negligible
2. There are no attractive forces between the particles

*non ideal conditions: low temperature, high pressure.