Chem Chapter 15

Energy

The capacity to do work or produce heat; exists as potential energy and kinetic energy.

Potential Energy

Energy that is stored in an object due to its composition or position.

Kinetic Energy

Energy of motion

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 or destroyed.

Chemical Potential energy

The energy stored in a substance because of its composition; most is absorbed or released as heat during chemical reactions or processes

Heat

A form of energy that flows form a warmer object to a cooler object

calorie

The amount of heat required to raise the temperature of one gram of pure water by one degree Celsius

Joule

The SI unit of heat and energy

Specific heat

The amount of heat required to raise the temperature by one gram of a given substance by one degree Celsius

Calorimeter

An insulated device that is used to measure the amount of heat released or absorbed during a physical or chemical process

Thermochemistry

The study of heat changes that accompany reactions and phase changes.

System

In thermochemistry, the specific part of the universe containing the reaction or process being studied

Surroundings

In thermochemistry, includes everything in the universe except for the system.

Enthalpy

The heat content of a system at constant pressure. (H)

Equation involving Enthalpy

Enthalpy of Reaction=Final Enthalpy-Initial Enthalpy

or

Enthalpy of reaction=Product Empathy-Reactant enthalpy

Enthalpy changes for _________ reactions are always negative

exothermic

Endothermic

Energy is absorbed by the chemical reaction

Exothermic

Energy is released by the chemical reaction

Enthalpy changes for _______ reactions are always positive

endothermic

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.

(Basically a balanced chemical equation)

Enthalpy of combustion

The enthalpy change for the complete burning of one mole of a given substance.

Molar enthalpy of fusion

The amount of heat required to melt one mole of a solid substance.

Molar enthalpy of vaporization

The amount of heat required to vaporize one mole of a solid substance

Molar Enthalpy of vaporization=

negative (-) molar enthalpy of condensation

Molar enthalpy of fusion=

negative (-) molar enthalpy of solidification

Combustion

The reaction of a fuel with oxygen

Hess’s Law

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.

standard enthalpy of formation

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 series.

Spontaneous process

A physical or chemical change that occurs without outside intervention and may require energy to be supplied to begin the process.

Entropy (s)

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.

Second law of thermodynamics

The spontaneous processes always proceed in such a way that the entropy of the universe increases

Heating Curve

What happens to a substance as it is heated

1 Joule in calories

0\.239 calories

1 calorie in joules

4\.184 Joules

1 CALORIE in kilocalories

1 kilocalorie

1 CALORIE in calories

1000 calories

variable “q”

heat absorbed/released (In joules)

variable “m”

Mass of sample (in grams)

variable “c”

Specific heat of the substance (J/gC) (C=Celsius)

variable “t”

the change in temperature (in Celsius) (T final- T initial)

Calculating heat equation

q= M x C x T

The SI Unit of heat and energy

Joule

The specific heat value that heats up the Fastest……

Is the smallest number and vice verse. Water is the slowest to heat up with its specific heat at 4.185