Matter and Energy II

Energy

is defined as the capacity to do work. Energy, unlike matter, cannot be seen, touched, smelled, or weighed but all of its form are capable of doing work.

Law of conservation of energy.

the total quantity of energy in the universe is assumed constant.

Heat

is the transfer of thermal energy between two bodies that are at different temperatures

Thermochemistry

is the study of heat change in chemical reactions

System

is the specific part of the universe that is of interest to us.

Surroundings

are the res of the universe outside the system.

Open system

can exchange mass and energy, usually in the form of heat with its surroundings.

Closed system

allows the transfer of energy (heat) but not mass.

Isolated system

does not allow the transfer of either mass or energy.

Calorimetry

is the measurement of heat changes.

Calorimeter

is a closed container designed specifically to measure heat changes.

Specific heat

of a substance is the amount of heat required to raise the temperature of one gram of the substance by one degree Celsius (J/g.°C).

Heat Capaciity

of a substance is the amount of heat required to raise the temperature of a given quantity of the substance by one degree Celsius (J/°C.)°°

Heat (q)

is a patch function, which values are dependent on the path taken. With specific heat and the amount of substance, change in the temperature predicts the amount of heat (q) absorbed or released in a particular process.

Constant-volume bomb calorimeter,

Heat of combustion is usually measured by placing a known mass of a compound in a steel container called a _____________ which is filled with oxygen at about 30 atm of pressure.

Enthalpy

is a thermodynamic quantity equivalent to the total heat content of a system. It is equal to the internal energy of the system plus he product of pressure and volume.

Thermochemical equations

shows the enthalpy change as well as the mass relationships. It is essential to specify a balanced equation when quoting the enthalpy change of a reaction.

Thermodynamics

deals with the interconversion of heat and other forms of energy.

Spontaneous reaction

If a reaction does occur under the given set of conditions.

Non-spontaneous reaction

If a reaction does not occur under specified conditions.

Exothermicity

favors the spontaneity of a reaction but does not guarantee it. Just as it is possible for an endothermic reaction to be spontaneous, it is possible for an exothermic reaction to be nonspontaneous.

First Law of Thermodynamics

states that energy can be converted from one form to another, but it cannot be created or destroyed.

Second Law of Thermodynamics

is defined as the entropy of the universe increases in a spontaneous process and remains unchanged in an equilibrium process.

Third Law of Thermodynamics

states that entropy of a perfect crystalline substance is zero at the absolute zero of temperature.