17.1 The Flow of Energy
Define thermochemistry.
The study of energy changes that occur during chemical reactions and changes in state.
Define calorimetry.
The precise measurement of the heat flow into or out of a system for chemical and physical processes.
When a vapor condenses, ____ is released.
heat
Define Hess's Law of Heat Summation.
if you add the thermochemical equations to each step to give you a final equation for the reaction.
Define endothermic process.
process of absorbing heat from surroundings
Define chemical potential energy.
The energy stored in the chemical bonds of a substance
Enthalpy
The heat content of a system at constant pressure.
A liquid that absorbs heat at its boiling point becomes a ____
vapor
Define standard heat of formation.
the change in enthalpy that accompanies the formation of a mole of a compound from its elements with all substances in their standard states.
Define exothermic process.
process that releases heat to surroundings
Define heat.
Energy that transfers from one object to another because of a temperature difference between them.
Define heat of combustion.
The heat of reaction for the complete burning of one mole of a substance
Define molar heat of solidification.
heat lost when one mole of a liquid is converted to a solid.
What does Hess's Law allow you to do?
To determine the heat of reaction indirectly
Define law of conservation of energy.
energy cannot be destroyed or created.
What determines the amount of energy stored in the substance?
The types of atoms and their arrangement in the substance determine the amount of energy stored in the substance.
How can the enthalpy change be written in a chemical equation?
In a chemical equation, the enthalpy change for the reaction can be written as either a reactant or a product.
Define molar heat of fusion.
heat absorbed by one mole of a substance as it melts to a liquid at a constant temperature.
How can you calculate the heat of reaction when it cannot be directly measured?
Hess's law allows you to determine the heat of reaction indirectly using other known heats of reactions.
Define heat of reaction.
the enthalpy change for the chemical equation exactly as it is written
What direction does heat flow in?
Heat always flows form a warmer object to a cooler object. If two objects remain in contact, both objects will be the same temperature.
How is the heat released by the related to the heat absorbed in a system?
In calorimetry, the heat released by the system is equal to the heat absorbed by its surroundings.
Define molar heat of solidification.
heat lost when one mole of a liquid solidifies.
Are diamonds made from heat? Do their forming involve thermochemistry?
YES and YES.
.238 cal equals how many joules?
1 joule