All Flashcards
Define exothermic process.
A process that releases heat to the surroundings; is negative.
Define endothermic process.
A process that absorbs heat from the surroundings; is positive.
What is the First Law of Thermodynamics?
Energy is conserved; it cannot be created or destroyed, only transferred or converted.
Define thermal equilibrium.
The state where heat flows until two objects reach the same temperature.
Define heat capacity.
The energy needed to raise 1 gram of a substance by 1 degree Celsius (J/g°C).
Define enthalpy ().
The heat change at constant pressure; indicates whether a reaction is exothermic or endothermic.
Define enthalpy of formation ().
The heat change when one mole of a compound is formed from its elements in their standard states.
What is a state function?
A property whose value does not depend on the path taken to reach a specific value.
Differentiate between exothermic and endothermic reactions in terms of and heat flow.
Exothermic: , heat is released. Endothermic: , heat is absorbed.
Compare calculating using bond enthalpies versus enthalpies of formation.
Bond Enthalpies: Uses bond breaking and forming energies. Enthalpies of Formation: Uses standard enthalpies of formation of products and reactants.
What is the effect of a negative value?
The reaction is exothermic, releasing heat to the surroundings.
What is the effect of a positive value?
The reaction is endothermic, absorbing heat from the surroundings.
What happens when heat is added to a substance with a high heat capacity?
The temperature of the substance increases less than a substance with a low heat capacity.