CHEMISTRY: Thermo Pt 1 Flashcards
(25 cards)
Energy
a measurement of the ability to do work.
Work
when a force is applied to an object and the object moves in the direction of the force.
Kinetic Energy
energy associated with motion
Potential Energy
stored energy
Physical changes
change in states/ forms (ex. melting of ice)
Chemical changes
rearrangements of atoms (ex. iron rusting)
Nuclear change
formation of new atoms (ex. nuclear fusion in the Sun)
1st law of thermodynamics
energy can change forms but is neither created nor destroyed!
Thermal energy
refers to the total kinetic energy of all entities in a substance (measured in J)
Temperature (T)
the measure of the average kinetic energy of the entities in a substance (measure in degrees celsius)
Heat (q)
a form of energy that describes the amount of thermal energy flown/transferred between substances, systems or surroundings. (measured in J)
Chemical system
the set of reactants and products undergoing the energy change
Surroundings
all of the matter around the system that is capable of absorbing or releasing thermal energy.
Open system
energy and matter can move in or out of the system
Closed system
only energy can move in or out of the system
Isolated system
neither energy nor matter can move in or out of the system
Exothermic reactions
rxn that releases energy in the form of light or heat. energy is a product and enthalpy change is negative. products have less energy than reactants. (ex. burning of a candle)
Endothermic reactions
rxn that absorbs energy from the surroundings. energy is a reactant and enthalpy change is positive. products have more energy that reactants. (ex. cooking an egg)
Calorimetry
an experimental technique used to measure the heat or energy changes in a chemical system.
Specific Heat Capacity
the quantity of heat required to raise the temperature of 1g to mass by 1 degree celsius of a substance.
Enthalpy
the total amount of thermal energy change.
Molar Enthalpy
the enthalpy change associated with a change involving 1 mol of substance. it is a constant measured in J/mol.
Bond dissociation energy
the average quantity of energy required to break a chemical bond
Standard enthalpy of formation
the change in enthalpy that accompanies the formation of 1 mol of a compound from its elements in their standard states
