Thermodynamics Vocab Unit 6

Calorimetry

the science of measuring heat flow

Calorimeter

the process of measuring the heat of chemical reactions or physical changes as well as heat capacity

Exothermic

refers to a reaction where energy (as heat) flows out of the system

Energy

the capacity to do work or to cause heat flow

Enthalpy

a property of a system equal to E + PV, where E is the internal energy of the system, P is the pressure of the system and V is the volume of the system. At constant pressure the change in enthalpy equals the energy flow as heat.

First Law of Thermodynamics

the energy of the universe is constant; same as the law of conservation of a liquid

Fossil Fuel

coal, petroleum, or natural gas; consists of carbon based molecules derived from decomposition of once living organisms

Greenhouse Effect

a warming effect exerted by the earth’s atmosphere (particularly CO2 and H2O) due to thermal energy retained by absorption of infrared radiation.

Heat

energy transferred between two objects due toa temperature difference between them

Heat Capacity

the amount of energy required to raise the temperature of an object by one degree Celsius

Hess’s Law

in going from particular set of reactants to a particular set of products, the enthalpy change is the same whether the reaction takes place in one step or in a series of steps; in summary, enthalpy is a state function.

Internal Energy

a property of a system that can be changed by a flow of work, heat, or both; E = q + w, where, E is the change in the internal energy of the system, q is heat, and w is work.

Kinetic Energy

½mv² energy due to the motion of an object; dependent on the mass of the object and the square of its velocity.

Law of Conservation of Energy

energy can be converted from one form to another but cannot be created nor destroyed.

Molar Heat Capacity

the energy required to raise the temperature of one mole of a substance by one degree Celsius.

Potential Energy

energy due to position or composition.

Specific Heat Capacity

the energy required to raise the temperature of one gram of a substance by one degree Celsius.

Standard Enthalpy of Formation

the enthalpy change that accompanies the formation of one mole of a compound at 25 degrees Celsius from its elements, with all substances in their standard states at the temperature.

Standard State

a reference for a specific substance defined according to a set of conventional.

State Function (property)

a property that is independent of the pathway

Surroundings

everything in the universe surrounding a thermodynamic system

Synthetic Gas

a mixture of a carbon monoxide and hydrogen, obtained by coal gasification.

System (thermodynamics)

that part of the universe on which attention is to be focused

Thermodynamics

the study of energy and its interconversions

Work

force acting over a distance

Endothermic

Refers to a reaction where energy (as heat) flows into the system

When is work positive?

If work is done on the system. [exothermic —> negative q (heat)]

When is work negative?

If work is done by the system. [endothermic —> positive q (heat)]