Unit 5.1 Gas Laws

Endothermic

(of a reaction or process) accompanied by or requiring the absorption of heat.

Exothermic

(of a reaction or process) accompanied by the release of heat. or (of a compound) formed from its constituent elements with a net release of heat.

Charles's Law

A law stating that the volume of an ideal gas at constant pressure is directly proportional to the absolute temperature.

Gay Lussac's Law

A law stating that the volumes of gases undergoing a reaction at constant pressure and temperature are in a simple ratio to each other and to that of the product.

Temperature

A measure of the intensity of heat, i.e. the hotness or coldness of a sample. or object.

Joule

A unit of energy in the SI system. One joule is 1 kg. m2/s2 which is also 0.2390 calorie.

Radiation

Energy sent out in the form of particles or waves.

Calorie

The amount of heat required to raise the temperature of one gram of water from 14.5°C to 15.5°C. 1 calorie = 4.184 joules.

Direct Relationship

between two numbers or other variables where an increase or decrease in one variable causes the same change to occur in the second variable.

Combined Gas Law

combines the three gas laws: Boyle's Law, Charles' Law, and Gay-Lussac's Law. It states the ratio of the product of pressure and volume and the absolute temperature of a gas is equal to a constant. PV/T = k.

Calorimeter

is a device used to measure the heat change or heat capacity of chemical reactions or physical changes.

Boyle's Law

is a gas law, stating that the pressure and volume of a gas have an inverse relationship, when temperature is held constant.

Law of conservation of energy

is a law of science that states that energy cannot be created or destroyed, but only changed from one form into another or transferred from one object to another.

Universal Gas Constant

is a physical constant which is featured in many fundamental equations in the physical sciences, such as the ideal gas law and the Nernst equation.

Kelvin

is a temperature scale designed so that zero degrees K is defined as absolute zero (at absolute zero, a hypothetical temperature, all molecular movement stops - all actual temperatures are above absolute zero) and the size of one unit is the same as the size of one degree Celsius.

Chemical Energy

is energy stored in the bonds of chemical compounds (atoms and molecules)

Mole Ratios

is ratio between the amounts in moles of any two compounds involved in a chemical reaction.

Potential Energy

is stored when an elastic is stretched, and converted to kinetic energy when the elastic is released.

STP

is the abbreviation for Standard Temperature and Pressure. STP most commonly is used when performing calculations on gases, such as gas density.

Enthalpy

is the amount of energy absorbed by the reaction; in exothermic reactions, it is the amount given off.

Specific Heat

is the amount of heat energy required to raise the temperature of a body per unit of mass.

Specific Heat Capacity

is the amount of heat energy required to raise the temperature of a substance per unit of mass.

Kinetic Energy

is the energy an object possesses due to its motion.

Heat

is the form of energy that flows between two samples of matter due to their difference in temperature.

Thermal Energy

is the internal energy of an object due to the kinetic energy of its atoms and/or molecules.

Avogadro's number

is the number of constituent particles, usually atoms or molecules, that are contained in the amount of substance given by one mole.

Calorimetry

is the science of measuring the heat of chemical reactions or physical changes.

Molar Volume

is the volume occupied by one mole of a substance (chemical element or chemical compound) at a given temperature and pressure.

Ideal Gas Law

law describing the relationship of the measurable properties of an ideal gas, where P (pressure) × V (volume) = n (number of moles) × R (the gas constant) × T (temperature in Kelvin).

Molar Mass

s a physical property defined as the mass of a given substance (chemical element or chemical compound) divided by the amount of substance.

Dalton's Law of Partial Pressures

states that the total pressure exerted by a mixture of gases is the sum of partial pressure of each individual gas present.

Conduction

the result of collisions between molecules; when one end of an object is heated, the molecules vibrate faster and the energy is transferred to their neighbors.

Convection

when heat is transferred by the mass movement of molecules from one place to another.