Thermochemistry Flashcards
What is gibbs free energy?
Gibbs free energy combines enthalpy and entropy into a single value. This quantity is the energy
associated with a chemical reaction that can be used to do work.
How does Gibb’s energy affect spontaneity?
Spontaneity decreases with gibbs energy.
What is the formula for gibbs energy?
ΔGo = −nF Ecello
Where: ΔGo is the standard free energy change n is the number of transferred electrons Eo is the standard cell potential F is the Faraday constant = 96500 C mol-1
What is Faradays constant?
96500 C mol-1
Formula for Nernst equation
E = Eo − (RT/ nF ) ln ( ([Product]) / [Reactant] )
E is the cell potential
Eo is the standard cell potential
R is the universal gas constant = 8.314 J/K/mole
T is the temperature
n is the number of transferred electrons
F is the Faraday constant = 96500 C mol-1
.
What is the universal gas constant?
8.314 J/K/mole
What are the main types of systems in thermochemistry?
Isolated, closed, and open.
What is an isolated system?
No anything in or out.
What is closed system?
No exchange of matter
What are thermodynamic properties?
Thermodynamic properties are defined as characteristic features of a system, capable of
specifying the system’s state.
Examples of thermodynamic properties
- Pressure
- Temperature
- Volume
- Entropy
- Internal energy
- Enthalpy
- Gibbs function
- Helmholtz functions.
How many types of physical properties of a system are there?
- Intensive and extensive.
What are intensive properties?
Intensive properties are properties that do not depend on the quantity of matter.
What are extensive properties?
Extensive properties are properties whose value depends on the mass of the
system.
What are examples of physical properties of a system.
Helmholtz free energy (F) Gibbs free energy (G) Enthalpy (H) Internal energy (U) Entropy (S) Volume (V) Temperature (T) Pressure (P)
What is enthalpy?
Determines the capability of a system to do work and release heat.
What is gibbs energy?
The thermodynamic potential that measures the maximum or reversible work by a thermodynamic system. Determines the feasibility of a reaction.
What is Helmholtz free energy?
The thermodynamic potential that measures useful work done by a closed thermodynamic
system
How many types of thermodynamic processes are there?
- Isobaric, isochoric, isothermal, adiabatic
What is an isobaric process?
• An isobaric process, during which the system’s pressure does not change.
What is isothermal process?
• An isothermal process, during which the system’s temperature remains constant.
What is adiabatic process?
• An adiabatic process, during which no heat is transferred to or from the system.
What is isochoric process?
• An isochoric process, during which the system’s volume does not change.
What is formula for enthalpy change?
ΔH = ΔU + ΔPV
where H = Enthalpy U = Internal energy P = Pressure V = Volume
