Chapter 6 Flashcards
biomass conversion
the process of applying chemical and biological methods to convert plant or animal matter into fuels
calorie (cal)
a unit of energy defined as exactly 4.184 joules; originally defined as the heat needed to raise the temperature of 1 g of water 1°C (from 14.5°C to 15.5°C)
calorimeter
a device used to measure the heat released or absorbed by a physical or chemical process taking place within it
change in enthalpy (delta H)
the change in the system’s internal energy plus the product of the constant pressure and the change in volume: ΔH = ΔE + PΔV; alternatively, the heat lost or gained at constant pressure: ΔH = qP.
coal gasification
an industrial process for altering the large molecules in coal to sulfur-free gaseous fuels
endothermic process
a process that occurs with an absorption of heat from the surroundings and therefore an increase in the enthalpy of the system (ΔH > 0)
enthalpy
a thermodynamic quantity that is equal to the system’s internal energy plus the product of the pressure and volume
enthalpy diagram
a graphic depiction of the enthalpy change of a system
exothermic process
a process that occurs with a release of heat to the surroundings and therefore a decrease in the enthalpy of the system (ΔH < 0
formation equation
an equation in which 1 mole of a compound forms from its elements
fossil fuel
any fuel, including coal, petroleum, and natural gas, derived from the products of the decay of dead organisms
heat (q)
the energy transferred between objects because of a difference in their temperatures only
heat capacity (C)
the quantity of heat required to change the temperature of an object by 1 K
Hess’ Law
a law stating that the enthalpy change of an overall process is the sum of the enthalpy changes of the individual steps
internal energy (E)
the sum of the kinetic and potential energies of all the particles in a system
joule (J)
the SI unit of energy; 1 J = 1 kg · m2/s2
law of conservation of energy (first law of thermodynamics)
a basic observation that the total energy of the universe is constant; thus, ΔEuniverse = ΔEsystem + ΔEsurroundings = 0
methanogenesis
the process of producing methane by anaerobic biodegradation of plant and animal waste
molar heat capacity (Cm)
the quantity of heat required to change the temperature of 1 mol of a substance by 1 K
photovoltaic cell
a device capable of converting light directly into electricity
pressure-volume work (PV work)
a type of mechanical work done when a volume change occurs against an external pressure
specific heat capacity (c)
the quantity of heat required to change the temperature of 1 gram of a substance or material by 1 K
standard enthalpy of formation
the enthalpy change occurring when 1 mol of a compound forms from its elements with all components in their standard states
standard enthalpy of reaction
the enthalpy change that occurs during a reaction when all components are in their standard states
standard state
a set of specific conditions used to compare thermodynamic data: 1 atm for gases behaving ideally, 1 M for dissolved species, or the pure substance for liquids and solids
state function
a property of a system determined only by the system’s current state, regardless of how it arrived at that state
surroundings
all parts of the universe other than the system being considered
system
the defined part of the universe under study
thermochemical equation
a balanced chemical equation that includes the enthalpy change for the reaction
thermochemistry
the branch of thermodynamics that focuses on the heat involved in chemical and physical change
thermodynamics
the study of energy and its transformations
work (w)
the energy transferred when an object is moved by a force
