Chem 4U: Unit 4 Vocab

Energy

The ability to do work

Conserved Quantity

Cannot be created or destroyed, just transferred or transformed

SI Units

International System of Units

Calorimetry

The science of measuring changes in energy

Isolated System

ONLY energy can enter or leave

Closed System

NEITHER matter nor energy enters or leaves

Open System

BOTH matter and energy can enter and leave

Surroundings

Everything outside a system’s boundary

System

The specific part of the universe being studied, separated from the rest of the universe by a boundary

Endothermic

The system gains energy from its surroundings

Exothermic

The system loses energy to its surroundings

Thermal Energy

Internal energy of a system that is directly related to the average kinetic energy of the particles and the number of particles present

Heat

Measure of the transfer of thermal energy between two objects when they touch

Temperature

Measure of the average kinetic energy of the particles in a given substance

Law of Conservation of Energy

Energy can be converted in form, but not created or destroyed

Elastic Potential

Energy stored in stretched objects

Nuclear Potential

Energy stored in the nucleus

Gravitational Potential

Energy stored by height

Chemical Potential

Energy stored in bonds

Electromagnetic Energy

Energy of light

Sound Energy

Energy of vibrating particles

Thermal Energy

Energy of moving particles

Potential Energy

Energy that is stored in some way but could be converted to kinetic energy under the right circumstances

Kinetic Energy

Energy associated with moving objects. The different types of kinetic energy are classified on what those objects are

Enthalpy

The energy of a system

Molar Enthalpy

The energy change associated with the reaction of one mole a substance

Specific Enthalpy

The energy change associated with the reaction of a substance per unit mass

Bomb Calorimeter

A device used for calorimetry, or the process of measuring the heat of chemical reactions or physical changes as well as heat capacity

Calorimeter

Device used to measure calorimetry

Fusion

Transition between solid and liquid phases (like melting or freezing)

Enthalpy Change

The energy absorbed or released from the surroundings when a system changes from reactants to products

Latent Heat

The energy absorbed/released during a phase change (no temperature change)

Enthalpy of Vaporization

The amount of energy required to vaporize/condense a given mass of a substance

Enthalpy of Fusion

The amount of energy required to melt/freeze a given mass of a substance

State Function

A property of a system whose value depends only on the system's current state, not on the path taken to reach it

Hess’s Law

States that the energy change for any chemical or physical process is independent of the pathway or number of steps required to complete the process provided that the final and initial reaction conditions are the same

Standard Enthalpy of Formation

The enthalpy change for 1 mole of a substance from elements in their standard state at SATP

Tangent Line

The instantenous rate of a curve

Instantaneous Rate

How fast a function changes at a single specific point, representing the slope of the tangent line at that point

Rate Law

Is a mathematical formula showing how a chemical reaction's speed (rate) depends on reactant concentrations

Overall Order of Reaction

The sum of the individual orders (exponents) of each reactant in the reaction's rate law

Orders of Reaction

Describes how the concentration of reactants affects the rate of a chemical reaction

Half-Life

The time required for half of the sample of a first order reaction to react

Collision Theory

For a reaction to occur reactant molecules must collide with energy greater than some minimum required value and with the proper orientation

Heterogenous Catalysts

Catalyst is in a different phase as the substances reacting

Homogeneous Catalysts

Catalyst is in the same phase as the substances reacting

Transition State Theory

An unstable grouping of atoms is formed in a collision with sufficient Ea. This molecule is called the Activated Complex

Activation Energy

The minimum energy required for two molecules to react

Reaction Mechanism

A series of elementary steps that makes up an overall reaction

Rate Determining Step

The slowest step in a reaction mechanism

Intermediate Molecules

Molecules formed as short-lived products in reaction mechanisms

Elementary Step

A step in a reaction mechanism that only involves one-, two-, or three-particle collisions