Key Terms Unit 2 Flashcards
Exothermic Reaction
Is one that releases energy to the surroundings, there is a temperature rise and ΔH is negative
Endothermic Reaction
Is on that takes in energy from the surroundings, there is a temperature drop and ΔH is positive
Enthalpy, H
Is the heat content of a system at constant pressure
Enthalpy Change
Is the heat content of a system at constant pressure
Principle of Conservation of Energy
States that energy cannot be created or destroyed only changed from one form into another
Hess’s law
States that the total enthalpy change for a reaction is independent of the route taken from the reactants to the products
Bond Enthalpy
Is the enthalpy required to break a covalent X - Y bond into X atoms and Y atoms, all in the gas phase
Average Bond Enthalpy
Is the enthalpy required to break a given type of bond in the molecules of a gaseous species
Rate of Reaction
Is the change in concentration of a reactant or product per unit time
Activation Energy
Is the minimum energy required to start a reaction by breaking bonds
Catalyst
Is a substance that increases the rate of a chemical reaction without being used up in the process. It increases the rate of reaction by providing an alternative route of lower activation energy
Homogenous Catalyst
Is in the same physical state as the reactants
Heterogenous Catalyst
Is in a different physical state from the reactants
Carbon Neutrality
Means that a chemical process such as fuel combustion does not lead to an increase in CO2 levels. Although the combustion does produce CO2 this is offset by the fact that the fuel has absorbed the same amount of CO2 in being made by photosynthesis
Functional Group
Refers to the atom/group of atoms that gives the compound its characteristic properties
Homologous Series
Is a series of compounds with the same functional group
Hydrocarbon
Is a compound of carbon and hydrogen only
Saturated Compound
Is one in which all the C to C bonds are single bonds
Unsaturated Compound
Contains C to C multiple bonds
Molecule Formula
Shows the atoms, and how many of each type there are, in a molecule of a compound
Displayed Formula
Shows all the bonds and atoms in the molecule
Shortened Formula
Shows the groups in sufficient detail that the structure is unambiguous
Skeletal Formula
Shows the carbon/hydrogen backbone of the molecule as a series of bonds with any functional group attached
The Empirical Formula
Is the formula of a compound with the atoms of the elements in their simplest integer ratio
Structural Isomers
Are compounds with the same molecular formula but with different structural formulae
Van Der Waals Forces
Are dipole-dipole or temporary dipole-temporary dipole interactions between atoms and molecules
Fossil Fuel
Is one that is derived from organisms that lived long ago