IB Chemistry HL Terms

Terms for the entire IB Chemistry HL syllabus.

Homogeneous mixture

A homogeneous mixture has uniform composition and properties throughout.

Heterogeneous mixture

A heterogeneous mixture has non-uniform composition, so its properties are not the same throughout.

Spectator ions

Spectator ions are the ions who do not take part in the reaction.

Mole

A mole of a substance with this number of fundamental units as there are atoms in exactly 12.00 g of ^{12}C.

Relative atomic mass

The relative atomic mass (*A_r*) of an element is the weighted average mass of one atom compared to one twelfth the mass of a carbon-12.

Relative isotopic mass

The relative isotopic mass is the mass of a particular atom of an isotope compared to one twelfth the mass of a carbon-12 atom.

Isotope

Isotopes are atoms of the same element that contain the same number of protons and electrons but a different number of neutrons.

Relative molecular mass

The relative molecular mass (*M_r*) is the weighted average mass of a molecule compared to one twelfth the mass of a carbon-12 atom.

Standard solutions

Stanrdard solutions are solutions with known concentrations.

Concentration

The concentration of a solution is the amount of solute dissolved in a solvent to make 1 dm^3 of solution.

Parts per million

1 ppm (parts per million) is a mass of 1 mg dissolved in 1 dm^3 of water.

Equivalence point

An equivalence point occurs when two solutions have reacted completely and is shown with the use of an indicator.

Spin-pair repulsion

Electrons with the same spin repel eachother, this is called spin-pair repulsion.

The rate of reaction

The rate of reactions is defined as the change in the amount or concentration of a particular reactant or product per unit time.

The order of a reactant

The order of a reactant shows how the reaction of a chemical, typically a reactant, affects the rate of reaction.

The overall order of reaction

The overall order of reaction is the sum of the powers of the reactants in a rate equation.

The rate constant

The rate constant, *k*, of a reaction can be calculated using the initial rates and the rate equation.

The rate-determining step

The rate-determining step is the slowest step in the reaction.

Unimolecular reaction

A unimolecular reaction has one species involved in the rate-determining step.

Bimolecular reaction

A bimolecular reaction har two species involved in the rate-determining step.

Oxidizing agent

An oxidizing agent is a substance that oxidizes another atom or ion by causing it to lose electrons.

Reducing agent

A reducing agent is a substance that reduces another atom or ion by causing it to gain electrons.

The Winkler Method

The Winkler Method is a technique used to measure dissolved oxygen in freshwater systems.

The biological oxygen demand (BOD)

The biological oxygen demand (BOD) is the amount of oxygen used to decompose the organic matter in a samlpe of water over a specified time period, usually 5 days, at a specified temperature.

Voltaic (or Galvanic) cells

A voltaic cell generates a potential difference known as an electromotive force (EMF), E.