Chemistry Thermodynamics Vocab (Chapter 15)

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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


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