Chapter 2 Energy from fuels Flashcards
Activation energy
The minimum energy required by reactants for a chemical reaction to occur. It is the energy required to break the bonds between the atoms of the reactants to allow products to form.
Avogadro’s number
The number of particles in one mole of any substance, equivalent to 6.023 x 10^23 particles.
Bond energy
The energy required to break a covalent bond.
Bond strength
The strength of a covalent bond. In general, the higher the bond energy the greater the bond strength.
Chemical energy
The sum of the chemical potential and kinetic energy in a substance. Chemical energy is stored in the bonds between atoms and molecules.
The energy results from things such as:
attractions between electrons and protons in atoms;
repulsion between nuclei;
repulsions between electrons;
movement of electrons ;
and vibrations and rotations around bonds.
Combustion reaction
A combustion reaction which takes place with sufficient oxygen. The products of complete combustion of hydrocarbons are carbon dioxide and water.
Endothermic
A reaction which absorbs energy from the surroundings. Delta H is positive.
Energy profile diagram
A diagram which shows the energy changes during a chemical reaction
Enthalpy
Heat content. The sum of chemical potential and kinetic energies in a substance; symbol H.
Enthalpy change
The difference in the total enthalpy of the products and the total enthalpy of the reactants, symbol Delta H. Also known as heat of reaction.
Enthalpy of combustion
The enthalpy released when a specified quantity (eg one mole or one gram) of a substance is burned completely in oxygen; symbol delta H
Exothermic
A reaction which releases energy to the surroundings. Delta H is negative.
Heat of combustion
The energy released when a specified quantity (eg 1 mole or 1 gram) of a substance burns completely in oxygen.
Heat of reaction
The difference in enthalpy between the reactants and products during a chemical reaction. Also known as enthalpy change.
Incomplete combustion
A combustion process that takes place when oxygen is limited. Incomplete combustion of hydrocarbons produces carbon and carbon monoxide as well carbon dioxide.
