Iwi Flashcards
What is the first law of thermodynamics?
The first law of thermodynamics states that energy cannot be created or destroyed, only transformed from one form to another.
What is the formula for internal energy change (ΔU)?
ΔU = Q +W, where Q is the heat added to the system and W is the work done by the system.
True or False: The enthalpy change at constant pressure is equal to the heat absorbed or released.
True
What is the formula for enthalpy (H)?
H = ◇U + P◇V,
H= ◇U+◇PV
H =◇U+◇nRT
where U is internal energy, P is pressure, and V is volume.
What does the symbol ‘Q’ represent in thermodynamics?
‘Q’ represents the heat added to or removed from a system.
Fill in the blank: The change in enthalpy (ΔH) for an exothermic reaction is _____ zero.
less than
What is the formula for work done by an expanding gas?
W = -PΔV, where P is pressure and ΔV is the change in volume.
What is the standard enthalpy of formation (ΔH°f)?
The standard enthalpy of formation is the change in enthalpy when one mole of a compound is formed from its elements in their standard states.
True or False: A system at equilibrium has no net change in the concentrations of reactants and products.
True
What is the formula for Gibbs free energy (G)?
G = H - TS, where H is enthalpy, T is temperature in Kelvin, and S is entropy.
What does a negative value of Gibbs free energy (ΔG) indicate?
A negative value of ΔG indicates that a process is spontaneous.
Fill in the blank: Entropy (S) is a measure of _____ in a system.
disorder
What is the relationship between entropy and the number of microstates?
Entropy increases with the number of microstates available to a system.
What is the formula for calculating the change in entropy (ΔS)?
ΔS = Q_rev / T, where Q_rev is the heat exchanged reversibly and T is the temperature.
True or False: Heat capacity at constant volume (C_v) is always less than heat capacity at constant pressure (C_p).
True
What is the relationship between C_p and C_v?
C_p = C_v + R, where R is the ideal gas constant.
What is the formula for the change in internal energy for an ideal gas?
ΔU = nC_vΔT, where n is the number of moles, C_v is the molar heat capacity at constant volume, and ΔT is the temperature change.
What does the term ‘adiabatic process’ mean?
An adiabatic process is one in which no heat is exchanged with the surroundings.
True or False: In an isothermal process, the temperature remains constant.
True
What is the formula for calculating work done in an isothermal process for an ideal gas?
W = 2.303nRT log(Vf/Vi), where Vf is the final volume and Vi is the initial volume.
What is the significance of the Carnot cycle?
The Carnot cycle is a theoretical cycle that represents the maximum possible efficiency of a heat engine.
What is the formula for efficiency (η) of a heat engine?
η = (W_out / Q_in) x 100%, where W_out is the work output and Q_in is the heat input.
Fill in the blank: The heat capacity ratio (γ) is defined as _____ / _____ .
C_p / C_v
