Chemistry Thermodynamics Vocab (Chapter 15)
Because 0ºC is equal to _______, individual temperatures have different numerical values on the two scales
273 kelvin
The amount of heat required to raise the temperature of one gram of pure water by one degree Celsius
Calorie
An insulated device that is used to measure the amount of heat released or absorbed during a physical or chemical process.
Calorimeter
The energy stored in a substance because of its composition; most is released or absorbed as heat during chemical reactions or processes.
Chemical Potential Energy
Identify five chemical processes where entropy is decreased
Condensing, crystallization, deposition, freezing, synthesis
The capacity to do work or produce heat; exists as potential energy, which is stored in an object due to its composition or position, and kinetic energy, which is the energy of motion.
Energy
The heat content of a system at constant pressure
Enthalpy
The enthalpy change for the complete burning of one mole of a given substance
Enthalpy Heat of Combustion
The change in enthalpy for a reaction—the difference between the enthalpy of the substances that exist at the end of the reaction and the enthalpy of the substances present at the start
Enthalpy Heat of Reaction
A measure of the number of possible ways that the energy of a system can be distributed; related to the freedom of the system's particles to move and the number of ways they can be arranged
Entropy
The energy available to do work—the difference between the change in enthalpy and the product of the entropy change and the kelvin temperature
Free Energy
_______ have greater standard entropies than liquids
Gases
_______ have the most freedom to move, so their standard entropies are the greatest
Gases
The thermodynamic quantity used to predict whether a reaction will occur spontaneously is _______ and is defined by the equation G = _______
Gibbs Energy, ∆H-T∆S
A form of energy that flows from a warmer object to a cooler object.
Heat
States that if two or more thermochemical equations can be added to produce a final equation for a reaction, then the sum of the enthalpy changes for the individual reactions is the enthalpy change for the final reaction
Hess's Law
The SI unit of heat and energy.
Joule
States that in any chemical reaction or physical process, energy may change from one form to another, but it is neither created nor destroyed.
Law of Conservation of Energy
The amount of heat required to melt one mole of a solid substance
Molar Enthalpy Heat of Fusion
The amount of heat required to vaporize one mole of a liquid.
Molar Enthalpy Heat of Vaporization
The symbol for standard entropy is _______ and the units used are _______ , the same as for molar heat capacity.
S, J/K mol
The spontaneous processes always proceed in such a way that the entropy of the universe increases
Second Law of Thermodynamics
The amount of heat required to raise the temperature of one gram of a given substance by one degree Celsius.
Specific Heat
A physical or chemical change that occurs without outside intervention and may require energy to be supplied to begin the process
Spontaneous Process
The change in enthalpy that accompanies the formation of one mole of a compound in its standard state from its constituent elements in their standard states
Standard Enthalpy Heat of Formation
In thermochemistry, includes everything in the universe except the system
Surroundings
In thermochemistry, the specific part of the universe containing the reaction or process being studied.
System
A balanced chemical equation that includes the physical states of all the reactants and the energy change, usually expressed as the change in enthalpy
Thermochemical Equation
The study of heat changes that accompany chemical reactions and phase changes
Thermochemistry
In thermochemistry, is the system plus the surroundings.
Universe
The only way/machine to measure energy is through a _______
calorimeter
A kelvin is the same temperature interval as a degree _______
celcius
Identify five chemical processes where entropy increases
combustion, decomposition, melting, sublimation, vaporization
A chemical reaction occurs if it is accompanied by a(n) [increase, decrease] in Gibbs energy.
decrease
All spontaneous processes occurs with _______ in Gibbs Energy
decrease
A system with more energy has more _______
disorder
The products of an [endothermic, exothermic] reaction have an energy higher than that of the reactants.
endothermic
The total energy content of a sample is its _______, and is represented by H
enthalpy
At very high temperatures, the sign and magnitude of G and the spontaneity of a reaction are determined primarily by the change in [enthalpy, entropy]
entropy
The property of a system that makes a process occur consists of two driving forces, a tendency toward the greatest _______ state and a tendency toward the lowest _______ state.
entropy, energy
In contrast, heat is an _______ property, which means that the amount of energy transferred as heat depends on the total amount of the sample
extensive
Th energy transferred between objects that are at different temperatures is _______
heat
According to the expression for G, the [higher, lower] the temperature for a positive entropy change, the greater the chances are that the reaction will be spontaneous.
higher
If a sample has a _______ temperature than its surroundings, energy is transferred from the sample. If the temperature is _______ than its surroundings, energy is transferred to the sample
higher, lower
The entropy of a substance _______ with temperature
increases
The temperature of a sample does no depend on the amount of the sample, there temperature is a _______ property
intensive
Heat, like other forms of energy, is measured in _______
joules
The SI unit of temperature is _______
kelvin
Therefore the energy change for heating or cooling without a phase change is equal to _______ x _______ x _______
mass, SH, delta T
The drive to achieve a state of [minimum, maximum] Gibbs energy may be interpreted as the driving force of a chemical reaction.
minium
The _______ enthalpy chant is the enthalpy change of one mole of an element or compound
molar
A process is spontaneous if ∆G is _______
negative
Because the atoms in a diamond are in a more ordered state than in graphite, the change in entropy in changing graphite into a diamond is _______
negative
A _______ enthalpy change means that the change releases energy or is a _______ process
negative, exothermic
The expression for G shows that when H is negative and S is positive, G is [positive, negative]. Thus, [endothermic, exothermic] reactions, which are accompanied by a(n) [increase, decrease] in entropy of the system, are probable.
negative, exothermic, increase
At _______, no disorder means no entropy
ok
Temperature and heat are different but related _______ properties
physical
A reaction is more likely to occur if the entropy is _______
positive
In endothermic reactions, H has a [positive, negative] value.
positive
A _______ enthalpy change means that the change requires energy and the process is _______
positive, endothermic
The expression for G shows that when H is positive and S is negative, G is [positive, negative]. This means that [endothermic, exothermic] reactions accompanied by a(n) [increase, decrease] in entropy are probable
positive, endothermic, decrease
The entropy change of a reaction is the standard entropy of the _______ minus the standard entropy of the _______
products, reactants
When a pure substance is heated or cooled, but does not change the energy as heat is the _______ as the enthalpy change
same
When the temperature of a system is low, the product T∆S is very [small, large] compared to the H term and has little influence on the value of G. In such cases, the reaction may occur as the [enthalpy, entropy] change predicts.
small, enthalpy
If G is negative, G, the reaction is [spontaneous, nonspontaneous].
spontaneous
The quantity of entropy possessed by 1 mol of a substance is called _______
standard
The _______ of a sample is a measure if the average kinetic energy of the particles in the sample
temperature
A temperature difference taken between two objects has _______ numerical value in kelvins and degrees Celsius
the same
The science that examines the energy change that accompanies chemical and physicals processes is called _______
thermodynamics
Equation for change in Gibbs Free Energy
∆G = ∆H - T∆S
Equation for change in Enthalpy
∆H = Hproducts- Hreactants
Equation for change in Entropy
∆S = Sproducts - Sreactants
