Thermodynamics Equations Flashcards

Questions and Answers

What does the equation $\Delta u = q + w$ represent?

First law of thermodynamics (correct)

Third law of thermodynamics

Entropic change

Second law of thermodynamics

What does the equation $w = Fd$ calculate?

Work

What is the equation for work done on a gas by its surroundings?

w = -P△V = Vfinal - Vinitial

How do you find the change in enthalpy?

△H = q - P△V + △PV Signup and view all the answers

What does the equation $q_p = \Delta u + P\Delta$ represent?

Heat at constant pressure Signup and view all the answers

What is the definition of enthalpy?

H = u + PV Signup and view all the answers

How is the change in enthalpy related to internal energy?

△H = △u Signup and view all the answers

What is the equation for finding enthalpy change in a constant pressure process?

△H = △u + P△V Signup and view all the answers

How do you calculate the change in energy?

△u = △q +/- △W Signup and view all the answers

List the equations for finding enthalpy/energy change at constant temperature.

<ol> <li>△u = △H - △(PV) 2) △u = △H - △nRT 3) △u = △H - RT△n</li> </ol> Signup and view all the answers

What is the formula for finding change in internal energy?

△u = △H - P△V Signup and view all the answers

How do you calculate heat capacity?

C = ms Signup and view all the answers

What does the equation $q = ms△t$ calculate?

Heat change in terms of specific heat Signup and view all the answers

What is the equation $q = C△t$ used for?

Finding heat change in terms of heat capacity Signup and view all the answers

What is the equation $q_{sys} = q_{cal} + q_{rxn}$ used for?

Finding heat absorbed (kJ) Signup and view all the answers

What does the equation $q_{rxn} = -q_{cal}$ represent?

Heat change in a reaction Signup and view all the answers

What is the equation for finding heat in a calorimeter when temperature changes?

q_{cal} = C_{cal} △t Signup and view all the answers

How do you calculate standard enthalpy of a reaction?

∆H_{rxn} = [\sigma] ∆H_{f (products)} - [\sigma] ∆H_{f (reactants)} Signup and view all the answers

What is the equation for finding the enthalpy of the final solution?

∆H_{soln} = ∆H_{soln} - ∆H_{components} Signup and view all the answers

What do the variables $u$, $H$, and $q$ represent?

Energy, enthalpy, heat Signup and view all the answers

Study Notes

First Law of Thermodynamics

Δu = q + w
Represents the internal energy change, where q is heat absorbed and w is work done.

Work Equations

w = Fd
Calculates work as the product of force (F) and distance (d).
w = -PΔV = Vfinal - Vinitial
Determines work done on the gas by the surroundings, using pressure and volume change.

Enthalpy Changes

ΔH = q - PΔV + ΔPV
Used for calculating changes in enthalpy.
q_p = Δu + PΔV
Represents heat at constant pressure.
ΔH = Δu + PΔV
Energy change for a process at constant pressure.

Internal Energy Changes

Δu = Δq +/- ΔW
Finds change in energy; negative sign indicates work done by the system, positive indicates work done on the system.
Δu = ΔH - PΔV
Used to find changes in internal energy.

Heat Capacity and Heat Change

C = ms
Formula for heat capacity where m is mass and s is specific heat.
q = msΔt
Calculates heat change using specific heat.
q = CΔt
Calculates heat change using heat capacity.

Calorimetry

q_sys = q_cal + q_rxn
Calculates total heat absorbed (in kJ) within a system.
q_rxn = -q_cal
Determines heat change in a chemical reaction.
q_cal = C_cal Δt
Finds heat change in a calorimeter due to temperature changes.

Reaction Enthalpy

ΔH_rxn = Σ ΔH_f (products) - Σ ΔH_f (reactants)
Standard enthalpy of a reaction calculation.
ΔH_soln = ΔH_soln - ΔH_components
Used for finding the enthalpy of the final solution based on components' enthalpies.

Key Variables

u = energy
H = enthalpy
q = heat
Fundamental concepts within thermodynamics.

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Description

Test your knowledge on key thermodynamics equations with these flashcards. Each card presents a fundamental equation and its definition, covering important concepts such as work, internal energy, and enthalpy. Perfect for students studying thermodynamics or preparing for exams.