DuckieDai Gibbs Free Energy Python Program

chemistry · MIT License

Overview

Calculate Delta G from Delta H, Delta S, and T or relate standard Gibbs energy to a dimensionless equilibrium constant.

Not calculator tested
Downloaded 33 times
Version 1.0.0
1808 bytes
Uses math

Download gibbs.py Read the source How to install

Before you run it

TI-84 Plus CE Python · No calculator OS or Python App version has been verified.
TI Connect CE .py transfer is the intended path; calculator OS, Python App, transfer, and execution have not yet been tested for this release
Delta H and Delta S are treated as temperature-independent for Delta G = Delta H - T*Delta S.
The K relation uses standard-state Delta G and a thermodynamic, dimensionless equilibrium constant.
Temperature and K must be positive; signed thermodynamic changes are accepted.

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Learn the math

How Gibbs free energy works

The idea

Gibbs free energy combines the heat change of a reaction with its change in disorder to tell you whether the reaction can happen without outside help.

A negative value means spontaneous. A positive value means the reverse direction is favored.

The formula

DG = DH - T*DS

DG0 = -R*T*ln(K)

DG: Gibbs free energy change (kJ/mol)
DH: enthalpy change (kJ/mol)
DS: entropy change (J/mol K)
T: temperature in kelvin
K: equilibrium constant

Using the program

1 finds DG from DH, DS, and T, and labels the result SPONTANEOUS or NONSPONTANEOUS.
2 finds the standard DG from an equilibrium constant. 3 finds K from a standard DG.
Press Enter at the end for a quick reference screen.

Worked example

For the formation of ammonia, DH = -92.2 kJ/mol and DS = -198.7 J/mol K. At 298 K, choose 1 and enter -92.2, -198.7, and 298.

DG = -92.2 - 298 x (-0.1987)

The program shows DG kJ/mol = -32.9874 and SPONTANEOUS.

Tips and common mistakes

Enter DS in J/mol K exactly as tables list it. The program converts it to kJ.
Temperature must be in kelvin: add 273.15 to degrees Celsius.
Spontaneous says nothing about speed. A spontaneous reaction can still be very slow.

Where this comes up

It is the center of the thermodynamics unit in general chemistry and AP Chemistry, and it links to equilibrium and electrochemistry. Biochemistry uses it to decide whether a metabolic step can proceed.

Exact reviewed bytes

Source code

Download .py

View source below, copy it when JavaScript is available, or download the exact .py bytes.

from math import log,exp

R=.008314

def duckiedai_intro(program_name,wait=True):
 title=program_name[:16]
 empty=16-len(title)
 left=empty//2
 right=empty-left
 print("+----------------------+")
 print("|   "+" "*left+title+" "*right+"   |")
 print("|                      |")
 print("|       __             |")
 print("|   ___(o )>  quack!   |")
 print("|   \\ <_. )           |")
 print("|    `---'             |")
 print("|     by DuckieDai     |")
 print("+----------------------+")
 print("Loading...")
 if wait:
  input("Press enter to start ")
  print("\n"*6)

def num(s):
 while 1:
  try:return float(input(s))
  except:print("Enter a number")

def pos(s):
 while 1:
  x=num(s)
  if x>0:return x
  print("Must be positive")

def menu():
 while 1:
  try:
   x=int(input("Choose 1-3: "))
   if x>0 and x<4:return x
  except:pass
  print("Choose 1 to 3")

def dg_type(g):
 if abs(g)<1e-7:print("AT EQUILIBRIUM")
 elif g<0:print("SPONTANEOUS")
 else:print("NONSPONTANEOUS")

def k_type(k):
 if abs(k-1)<1e-7:print("K=1 equilibrium")
 elif k>1:print("Products favored")
 else:print("Reactants favored")

duckiedai_intro("GIBBS ENERGY")
print("GIBBS FREE ENERGY")
print("1 DG from H,S,T")
print("2 DG from K")
print("3 K from DG")
c=menu()

if c==1:
 h=num("DH kJ/mol: ")
 s=num("DS J/mol K: ")
 t=pos("Temp K: ")
 g=h-t*s/1000
 print("DG kJ/mol =",g)
 dg_type(g)

elif c==2:
 k=pos("K: ")
 t=pos("Temp K: ")
 g=-R*t*log(k)
 print("DG kJ/mol =",g)
 dg_type(g)
 k_type(k)

else:
 g=num("DG kJ/mol: ")
 t=pos("Temp K: ")
 try:
  k=exp(-g/(R*t))
  print("K =",k)
  k_type(k)
 except:print("K too large")

input("ENTER for guide: ")
print("QUICK GUIDE")
print("DG<0: spontaneous")
print("DG>0: nonspontaneous")
print("K>1: products")
print("K<1: reactants")
print("DuckieDai: done!")
input("ENTER to exit: ")

from math import log,exp
R=.008314
def duckiedai_intro(program_name,wait=True):
title=program_name[:16]
empty=16-len(title)
left=empty//2
right=empty-left
print("+----------------------+")
print("| "+" "*left+title+" "*right+" |")
print("| |")
print("| __ |")
print("| ___(o )> quack! |")
print("| \\ <_. ) |")
print("| `---' |")
print("| by DuckieDai |")
print("+----------------------+")
print("Loading...")
if wait:
input("Press enter to start ")
print("\n"*6)
def num(s):
while 1:
try:return float(input(s))
except:print("Enter a number")
def pos(s):
while 1:
x=num(s)
if x>0:return x
print("Must be positive")
def menu():
while 1:
try:
x=int(input("Choose 1-3: "))
if x>0 and x<4:return x
except:pass
print("Choose 1 to 3")
def dg_type(g):
if abs(g)<1e-7:print("AT EQUILIBRIUM")
elif g<0:print("SPONTANEOUS")
else:print("NONSPONTANEOUS")
def k_type(k):
if abs(k-1)<1e-7:print("K=1 equilibrium")
elif k>1:print("Products favored")
else:print("Reactants favored")
duckiedai_intro("GIBBS ENERGY")
print("GIBBS FREE ENERGY")
print("1 DG from H,S,T")
print("2 DG from K")
print("3 K from DG")
c=menu()
if c==1:
h=num("DH kJ/mol: ")
s=num("DS J/mol K: ")
t=pos("Temp K: ")
g=h-t*s/1000
print("DG kJ/mol =",g)
dg_type(g)
elif c==2:
k=pos("K: ")
t=pos("Temp K: ")
g=-R*t*log(k)
print("DG kJ/mol =",g)
dg_type(g)
k_type(k)
else:
g=num("DG kJ/mol: ")
t=pos("Temp K: ")
try:
k=exp(-g/(R*t))
print("K =",k)
k_type(k)
except:print("K too large")
input("ENTER for guide: ")
print("QUICK GUIDE")
print("DG<0: spontaneous")
print("DG>0: nonspontaneous")
print("K>1: products")
print("K<1: reactants")
print("DuckieDai: done!")
input("ENTER to exit: ")

Filename: gibbs.py
Size: 1808 bytes
SHA-256: f769c7eb1f0f7d39975b4219deccf44dd5da9ed62f0d99a831b3fcd0675813c7

Usage

Inputs

Delta H in kJ/mol, Delta S in J/(mol*K), and temperature in K
Dimensionless equilibrium constant K or standard Delta G in kJ/mol

Outputs

Delta G in kJ/mol or equilibrium constant K
A sign or equilibrium-position interpretation with stated boundaries

Units: Temperature is kelvin; energy is kJ/mol; entropy input is J/(mol*K); R is 0.008314 kJ/(mol*K); K is dimensionless.

Assumptions and limitations

Assumptions

Delta H and Delta S are treated as temperature-independent for Delta G = Delta H - T*Delta S.
The K relation uses standard-state Delta G and a thermodynamic, dimensionless equilibrium constant.

Constraints

Temperature and K must be positive; signed thermodynamic changes are accepted.

Known failures

The sign of Delta G describes thermodynamic direction under stated conditions, not reaction rate.
Very large positive Delta G can underflow K to zero at display precision.

Compatibility and review

Review status: Not calculator tested
Tested on: The owner reports personally testing the supplied archive programs on a calculator; exact model, OS, and Python App versions were not recorded
What happened: Owner reported interactive testing is disclosed, but the published bytes are not labeled independently calculator tested because the environment is unrecorded and Arrhenius received a narrow intake correction
Dependencies: math
Suggested calculator name: GIBBS — you can give it another valid, unique name when you transfer it
Desktop test cases: Not available for this interactive-only source

This exact source auto-launches an interactive calculator session, so compatibility evidence comes from the recorded physical-device review rather than an importable desktop fixture.

Transfer and launch

Download the .py file, send it to your calculator with TI Connect CE as GIBBS or another name, then open the Python App and try the worked example on this page first. This release has no verified calculator OS or Python App version; treat transfer and execution as unverified until independently tested.

Full installation and troubleshooting guide. Check your teacher's or exam's rules before using any program.

Version history

1.0.0 — current version, published 2026-09-23. Download this reviewed version

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