Flashcards for Chapter 15 in Chemistry

What are surroundings?
in thermochemistry, includes everything in the universe except the system
What is Hess’s Law?
States that if two or more thermochemical equations an 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
What is a calorie?
the amount of heat required to raise the temperature of one gram of pure water by one degree celsius
What is a joule?
the SI unit of heat and energy
What is a spontaneous process?
a physical or chemical change that occurs without outside intervantion and may require energy to be supplied to begin the process
What is a system?
in thermochemistry, the specific part of the universe containing the raction or process being studied
What is a thermochemical equation?
a balanced chemical equation that includes the physical states of all the reactants and the energy change, usually expressed as the change in enthalpy
What is chemical potential energy?
the energy stored in a substance because of its composition; most is released or absorbed as heat during chemical reactions or processes
What is energy?
the capacity to do work or produce heat; exists as potential energy, which is stored in an objectdue to its composition or position, and kinetic energy which is the energy of motion
What is enthalpy of combustion? (possible fill in the blank)
the enthalpy change for the complete burning of one mole of a given substance
What is enthalpy?
the heat content of a system at constant pressure
What is entropy?
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
What is free energy?
the energy available to do work the difference between the change in enthalpy and the product of the entropy change and the kelvin temperature
What is heat?
a form of energy that flows from a warmer object to a cooler object
What is molar enthalpy of fusion? (possible fill-in-the-blank)
the amount of heat required to melt one mole of a solid substance
What is molar enthalpy of vaporization? (fill-in-the-blank?)
the amount of heat required to vaporize one mole of a liquid
What is specific heat?
the amount of heat required to raise the temperature of one gram of a given substance by one degree celsius
What is standard enthalpy of formation?
the change in enthalpy that accompanies the formation of one mole of a compound in its standard statefrom its constituent elements in their standard states
What is the Second Law of Thermodynamics?
the spontaneous processes always proceed in such a way that the entropy of the universe increases
What is the enthalpy of a reaction?
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
What is the law of conservation of energy?
states that in any chemical reaction or physical process, energy may change from one form to another, but it is neither created nor destroyed
What is the universe?
in thermochemistry, is the system plus the surroundings
What is thermochemistry?
the study of heat changes that accompany chemical reactions and phase changes
What is a calorimeter?
an insulated device that is used to measure the amount of heat released or absorbed during a physical or chemical process
What does a triangle before a H mean/stand for?
the change in enthalpy
What does the triangle before a S mean?
the change in entropy
What is the standard state of formation?
It is 25*C per 1 atm
How many joules are in one calorie?
4.184 Joules
What is the specific heat for water?
4.184 J/(g)*C
Is the change in entropy positive or negative if it is a solid to a liquid and a liquid to a gas?
positive
Is the change in entropy positive or negative if a gas is being dissolved in a solvent?
negative
Is the change in entropy positive or negative if the number of gaseous product particles is greater than the number of gaseous reactant particles?
positive
Does entropy increase or decrease if a solid or a liquid dissolves in a solvent?
increases
What does the random motion of the particls of a substance do as its temperature increases?
it increases
How is the value of the change in enthalpy of vaporization related to the change in enthalpy of condensation?
enthalpy of condensation has the opposite sign of the value of the enthalpy of vaporization
How is the value of the enthalpy of fussion related to the enthalpy of solid?
the enthalpy of a solid has the opposite sign of the value of the enthalpy of fussion
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