Thermochemistry Flashcards
Thermodynamics Introduction
Heat
- speed or Energy of particles
Thermodynamics Introduction
Energy
Capacity to do work
Thermodynamics Introduction
Work
Action of Force through ∆x
Thermodynamics Introduction
Total Energy of object
- KE: E associated with motion ==> Thermal Energy
- PE: (bond energy); energy associated with position or composition
Energy Units
1 L*atm
101.325 J
Energy Transfer
Energy Transfer between system and surroundings
- Sys decrease(-) = Increase surroundings(+)
- Sys increase(+) = Decrease surroundings(-)
Definition of Specific Heat(c)
- Amount of energy required to raise 1 gram by 1 C
Exothermic vs Endothermic
Exothermic
- Graph increases then ends lower than starting level(∆ PE = -)
Exothermic vs Endothermic
Endothermic
- Graph increases then ends higher than starting level(∆ PE = +)
Types of Systems
Open
- matter and Energy exchanged with surroundings
Types of Systems
Closed
- Only Energy may exchange with surroundings but not matter
Type of System
Insulated
- No energy or matter exchanged with surroudings
Transfer between system and surroundings
Energy Transfer with work and heat
- E = q + w
Transfer between system and surroundings
Heat/Q
- Driving Force = ∆T
Transfer between system and surroundings
Work/W
- Driving Force = - P * ∆V
- W= Fd
- Compression = (+)
- Expansion = (-)
Heat
Heat Capacity
- C
- q=C∆T
- slope of Q and ∆T
- units = J/C
- Extensive: Depends on mass
Heat
Specific Heat
- c
- c = Q/m/∆T
Calorimeter
Bomb
- Constant Volume
- qcal=Ccal* ∆T
- qcal = qrxn = ∆Erxn
Calorimeter
Coffee-Cup
- Constant Pressure
- qcal=Ccal* ∆T
- qcal = qrxn = ∆Erxn
Standard Enthalpy of Formation
Standard State
- State of Pure Substance at l atm P and Temp of Interest(25 C)
Standard Enthalpy of Formation
Standard Enthalpy of change
- ∆H^o
- ∆H of reactants and products
Standard Enthalpy of Formation
Standard Enthalpy of Formation
- ∆H when 1 mol substance formed from compund standard state elements
Standard Enthalpy of Formation
Standard Enthalpy of Formation Equation
- ΔHoreaction=ΣΔHof(p)−ΣΔHof(r)
Hess’ Law
Hess’ Law
- If equation can be explained as sum of 2+ equations, ∆ H for desired equation = ∆ H sum of other equation
Phase Changes
Heat absorbed into system
- q > 0
- melting, vaporization, sublimation
Phase Changes
Heat released into system
- q < 0
- freezing, condensation, deposition
