Energetics Flashcards
(10 cards)
What is an exothermic reaction?
reaction that releases heat to the surroundings (temperature increases).
What is an endothermic reaction?
A reaction that absorbs heat from the surroundings (temperature decreases).
What is enthalpy change (ΔH)?
The heat energy change at constant pressure, measured in kJ/mol.
What is the sign of ΔH in an exothermic reaction?
Negative (–ΔH).
What is the sign of ΔH in an endothermic reaction?
Positive (+ΔH).
What is the standard enthalpy change of reaction
The enthalpy change under standard conditions: 100 kPa, 25 degrees Celsius and substances in their standard states.
What is the formula for calculating heat energy (q)?
q = mcΔT
(m = mass of solution in g, c = specific heat capacity
What is Hess’s Law?
The total enthalpy change of a reaction is the same, no matter the route taken.
What are bond enthalpies?
The energy required to break one mole of bonds in a gaseous molecule.
What is the enthalpy of combustion?
The enthalpy change when one mole of a substance is completely burned in oxygen.
