Under what condition(s) is the enthalpy change of a process equal to the amount of heat transferred into or outof the system? (a) temperature is constant (b) pressure is constant (c) volume is constant

Thermochemistry is the study of heat energy associated with chemical reactions and phase changes.  Thermochemistry involves the following concepts: Heat of reaction: Also known as the enthalpy of reaction, this looks at the overall heat energy that occurs in a reaction. Enthalpy: The heat content of a system. Hess's law: A principle in general chemistry that states that the change in enthalpy for a reaction is independent of path and depends only on initial and final states. Closed system: A thermodynamic system that exchanges neither energy nor matter with its surroundings. A covered... Show more

Thermochemistry is the study of heat energy associated with chemical reactions and phase changes. 

Thermochemistry involves the following concepts:
Heat of reaction: Also known as the enthalpy of reaction, this looks at the overall heat energy that occurs in a reaction.
Enthalpy: The heat content of a system.
Hess's law: A principle in general chemistry that states that the change in enthalpy for a reaction is independent of path and depends only on initial and final states.
Closed system: A thermodynamic system that exchanges neither energy nor matter with its surroundings. A covered pot on the stove is approximately a closed system. 

Thermochemical reactions can be either endothermic or exothermic:
Endothermic reactions: Absorb heat energy.
Exothermic reactions: Evolve heat energy. In exothermic reactions, more energy is released when the bonds are formed in the products than is used to break the bonds in the reactants. 

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