Flashcards
enthalpy
Cards in this deck (13)
- 1Conservation of Energy 1st Law of ThermodynamicsEnergy can neither be created nor destroyed - it can only change form
The total Energy of the universe is constant
= 1st Law of Thermodynamics - 2SystemSystem = part of universe under study (e.g. - chemicals in a flask)
- 3SurroundingsSurroundings = the rest of the universe (or as much as needed (e.g. - the flask)
- 4UniverseUniverse = System + Surrounds
- 5Internal EnergyInternal Energy depends on:
Temperature
Type of material (mass and particles)
Amount of material (number of particles) - 6Calculating Thermodynamic ChangesEnergy change of a final system =
ΔE = E final - E initial - 7—ΔE positive : internal energy increases
- 8—ΔE negative : internal energy decreases
- 9Heat CapacityHeat capacity = E required to raise the T(temperature) of an object by 1°C
Specific Heat Capacity = E required to heat 1 gram of substance by 1°C
Molar Heat Capacity = E required to heat 1 mole of substance by 1°C - 10Specific HeatEnergy required to change Temp of an object is:
Heat required =
mass x specific heat x ΔTq = m c ΔT
or…
Heat required = moles x molar heat capacity x ΔT
q = n cm ΔT - 11When heat is ADDED to a systemq (heat) is positive
the change is endothermic
temperature decreases
(liquid water boils to become gaseous water) - 12When heat is REMOVED from a systemq (heat) is negative
the change is exothermic
temperature increases
(gaseous water condenses to become liquid water) - 13—