Formulae Flashcards
What is the first law of thermodynamics?
Energy cannot be created or destroyed, only transformed.
What is the formula for internal energy change (ΔU)?
ΔU = Q - W, where Q is heat added and W is work done by the system.
True or False: The entropy of an isolated system always increases.
True
What is the formula for calculating entropy change (ΔS)?
ΔS = Q_rev / T, where Q_rev is the reversible heat and T is the temperature in Kelvin.
Fill in the blank: The ideal gas law is expressed as ______.
PV = nRT
What does ‘P’ stand for in the ideal gas law?
Pressure
What is the relationship expressed by the Gibbs free energy equation?
G = H - TS, where G is Gibbs free energy, H is enthalpy, T is temperature, and S is entropy.
What is the formula for enthalpy change (ΔH) at constant pressure?
ΔH = ΔU + PΔV
True or False: In a spontaneous process, ΔG is positive.
False
What is the formula for calculating work done in an isothermal process for an ideal gas?
W = nRT ln(Vf / Vi)
Fill in the blank: The heat capacity at constant volume is denoted as ______.
Cv
What is the formula for calculating the change in internal energy for an ideal gas?
ΔU = nCvΔT
What does ‘n’ represent in thermodynamic equations?
The number of moles of the substance.
What is the significance of the Helmholtz free energy (A)?
A = U - TS, where A is Helmholtz free energy, U is internal energy, T is temperature, and S is entropy.
What is the formula for calculating the efficiency of a Carnot engine?
Efficiency = 1 - (Tc / Th), where Tc is the cold reservoir temperature and Th is the hot reservoir temperature.
True or False: Heat is a state function.
False
What is the relationship between enthalpy and internal energy for a system at constant pressure?
ΔH = ΔU + PΔV
Fill in the blank: The critical point is defined by the temperature and pressure at which ______.
The distinction between liquid and gas phases disappears.
What does ‘R’ represent in the ideal gas law?
The ideal gas constant.
What is the formula for calculating the work done during an adiabatic process?
W = ΔU = -Q
True or False: A process is isothermal if the temperature remains constant.
True
What is the formula to calculate the change in entropy for a phase transition?
ΔS = ΔH/T, where ΔH is the enthalpy change and T is the temperature.
What is the significance of the second law of thermodynamics?
It states that the total entropy of an isolated system can never decrease over time.
What is the formula for calculating the Gibbs free energy change at equilibrium?
ΔG = 0
