Cat Lab · An evolving scientific computing workspace
A free calculation workspace on Nate Shakouri’s personal Chemecat site.
CAT LAB · STEADY-STATE CALCULATIONS
Mass & Energy Balance
Follow the material. Account for the energy. Inspect every check.
Methane combustion example loaded. Demonstration inputs are not measurements. Inputs stay in this tab; download a record before leaving. Changes of compatible units preserve the entered quantity.
Process & reaction
Use neutral formulas, coefficients and →, -> or =. For example: CH4 + 2 O2 -> CO2 + 2 H2O. Add (g), (l) or (s) to specify phase.
Explicit phase suffixes take precedence. A selected phase is an assumption, not a phase-equilibrium prediction.
Interpreted reaction
CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g)
PASS Elemental stoichiometry balanced
- CH4 · gas · explicit phase
- O2 · gas · explicit phase
- CO2 · gas · explicit phase
- H2O · gas · explicit phase
Elemental validation
C residual0 1
Σ_i a_C,i ν_i = 0 (mol atoms/mol reaction)
((0 1 + (1 × -1)) + (1 × 1))
Engine value: 0 1. Dimensions checked in SI.
H residual0 1
Σ_i a_H,i ν_i = 0 (mol atoms/mol reaction)
((0 1 + (4 × -1)) + (2 × 2))
Engine value: 0 1. Dimensions checked in SI.
O residual0 1
Σ_i a_O,i ν_i = 0 (mol atoms/mol reaction)
(((0 1 + (2 × 1)) + (1 × 2)) + (2 × -2))
Engine value: 0 1. Dimensions checked in SI.
A balancing proposal never changes the feed or confirms the reaction. Confirmation adds missing reactants with blank feed values for you to enter.
Mixed feed
Enter measured or specified values. Every formula and phase identifies a component; products or inerts already in the feed may be included.
Required for energy; material results do not require temperature.
No real-gas pressure correction or phase check.
Species & property data
Formula determines elemental composition and molecular weight. Thermodynamic properties require the correct chemical identity and phase.
Formation properties and entropy use 298.15 K, 1 bar and standard elements. Manual entries supplement or override the selected reference record. Missing values remain unknown.
CH4 · gasMethaneΔfH° available
Cp available
A formula can represent multiple isomers. Choose the intended identity; the calculator does not infer structure.
- Standard formation enthalpy, ΔfH°
- -74.8731 kJ/molReference · NIST Chemistry WebBook SRD 69: Methane, gas Shomate data
- Standard formation Gibbs energy, ΔfG°
- Missing
- Standard molar entropy, S°
- 186.251 J/(mol·K)Reference · NIST-JANAF CH4: standard entropy at 298.15 K
- Heat capacity, Cp
- Shomate · 298–1300 K; 1300–6000 KReference · NIST Chemistry WebBook SRD 69: Methane, gas Shomate data
O2 · gasOxygenΔfH° available
Cp available
A formula can represent multiple isomers. Choose the intended identity; the calculator does not infer structure.
- Standard formation enthalpy, ΔfH°
- 0 kJ/molReference · NIST Chemistry WebBook SRD 69: Oxygen, gas Shomate data
- Standard formation Gibbs energy, ΔfG°
- Missing
- Standard molar entropy, S°
- 205.147 J/(mol·K)Reference · NIST-JANAF O2: standard entropy at 298.15 K
- Heat capacity, Cp
- Shomate · 100–700 K; 700–2000 K; 2000–6000 KReference · NIST Chemistry WebBook SRD 69: Oxygen, gas Shomate data
CO2 · gasCarbon dioxideΔfH° available
Cp available
A formula can represent multiple isomers. Choose the intended identity; the calculator does not infer structure.
- Standard formation enthalpy, ΔfH°
- -393.5224 kJ/molReference · NIST Chemistry WebBook SRD 69: Carbon dioxide, gas Shomate data
- Standard formation Gibbs energy, ΔfG°
- Missing
- Standard molar entropy, S°
- 213.795 J/(mol·K)Reference · NIST-JANAF CO2: standard entropy at 298.15 K
- Heat capacity, Cp
- Shomate · 298–1200 K; 1200–6000 KReference · NIST Chemistry WebBook SRD 69: Carbon dioxide, gas Shomate data
H2O · gasWater vaporΔfH° available
Cp available
A formula can represent multiple isomers. Choose the intended identity; the calculator does not infer structure.
- Standard formation enthalpy, ΔfH°
- -241.8264 kJ/molReference · NIST Chemistry WebBook SRD 69: Water vapor, gas Shomate data
- Standard formation Gibbs energy, ΔfG°
- Missing
- Standard molar entropy, S°
- 188.834 J/(mol·K)Reference · NIST-JANAF H2O: standard entropy at 298.15 K
- Heat capacity, Cp
- Shomate · 500–1700 K; 1700–6000 KReference · NIST Chemistry WebBook SRD 69: Water vapor, gas Shomate data
Missing thermal properties do not prevent a valid material balance. Energy and adiabatic results are withheld when their required data or temperature coverage are unavailable.
Reaction specification
Conversion and extent are specified inputs. Kinetics, equilibrium and selectivity are not predicted.
Infeasible entries remain visible and are rejected.
Feed feasibility
Limiting reactant(s): CH4(g), O2(g)
Maximum feasible extent rate1 mol/s
ξ̇_max = min_reactants(ṅ_i,in / (−ν_i))
1 mol/s
Engine value: 1 mol/s. Dimensions checked in SI.
Maximum target conversion100 %
X_max,r = min_i[(ṅ_i,in / ṅ_r,in) (−ν_r)/(−ν_i)]
1
Engine value: 1 1. Dimensions checked in SI.
Applied target conversion100 %
X_r = specified reacted fraction of reference-reactant feed
1
Engine value: 1 1. Dimensions checked in SI.
Reactant availability
CH4(g)
Available molar flow1 mol/s
ṅ_i,in = Σ inlet component flows
(0 mol/s + 1 mol/s)
Engine value: 1 mol/s. Dimensions checked in SI.
Extent limit1 mol/s
ξ̇_max,i = ṅ_i,in / (−ν_i)
((0 mol/s + 1 mol/s) / 1)
Engine value: 1 mol/s. Dimensions checked in SI.
O2(g)
Available molar flow2 mol/s
ṅ_i,in = Σ inlet component flows
(0 mol/s + 2 mol/s)
Engine value: 2 mol/s. Dimensions checked in SI.
Extent limit1 mol/s
ξ̇_max,i = ṅ_i,in / (−ν_i)
((0 mol/s + 2 mol/s) / 2)
Engine value: 1 mol/s. Dimensions checked in SI.
Outlet, heat & work
Specified final temperature. Requires supported heat-capacity coverage.
Optional context; pressure drop and phase equilibrium are not solved.
Positive out of the system. Enter 0 explicitly for no shaft work.
Energy convention: Q − W + Hin − Hout = 0. Formation and sensible enthalpy are included once; reaction heat is not added again.
Species & material balance
Current inputs only. Expand quantities for equations, substitutions, SI values and sources. Generated closure checks model consistency; it is not experimental validation.
CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g)
Applied reaction extent rate1 mol/s
ξ̇ = ṅ_r,in X_r / (−ν_r)
1 mol/s
Engine value: 1 mol/s. Dimensions checked in SI.
| Species / phase | Inlet mol/s | Generated mol/s | Consumed mol/s | Outlet mol/s | MW g/mol | Inlet kg/s | Outlet kg/s |
|---|---|---|---|---|---|---|---|
| CH4(g) | 1 | 0 | 1 | 0 | 16.043 | 0.016043 | 0 |
| CO2(g) | 0 | 1 | 0 | 1 | 44.009 | 0 | 0.044009 |
| H2O(g) | 0 | 2 | 0 | 2 | 18.015 | 0 | 0.03603 |
| O2(g) | 2 | 0 | 2 | 0 | 31.998 | 0.063996 | 0 |
Species calculations & residuals
CH4(g)
Molecular weight16.043 g/mol
M_i = Σ_k a_ki M_k
((0 kg/mol + (1 × 0.012011 kg/mol)) + (4 × 0.001008 kg/mol))
Engine value: 0.016042999999999998 kg/mol. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Inlet molar flow1 mol/s
ṅ_i,in = Σ inlet streams
(0 mol/s + 1 mol/s)
Engine value: 1 mol/s. Dimensions checked in SI.
Generated molar flow0 mol/s
generation_i = max(ν_i,0) ξ̇
(0 × 1 mol/s)
Engine value: 0 mol/s. Dimensions checked in SI.
Consumed molar flow1 mol/s
consumption_i = max(−ν_i,0) ξ̇
(1 × 1 mol/s)
Engine value: 1 mol/s. Dimensions checked in SI.
Outlet molar flow0 mol/s
ṅ_i,out = Σ actual outlet streams
(0 mol/s + 0 mol/s)
Engine value: 0 mol/s. Dimensions checked in SI.
Inlet mass flow0.016043 kg/s
ṁ_i,in = ṅ_i,in M_i
((0 mol/s + 1 mol/s) × 0.016043 kg/mol)
Engine value: 0.016042999999999998 kg/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Outlet mass flow0 kg/s
ṁ_i,out = ṅ_i,out M_i
((0 mol/s + 0 mol/s) × 0.016043 kg/mol)
Engine value: 0 kg/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Species accounting residual0 mol/s
0 = inlet − outlet + generation − consumption (steady state)
((((0 mol/s + 1 mol/s) − (0 mol/s + 0 mol/s)) + (0 × 1 mol/s)) − (1 × 1 mol/s))
Engine value: 0 mol/s. Dimensions checked in SI.
CO2(g)
Molecular weight44.009 g/mol
M_i = Σ_k a_ki M_k
((0 kg/mol + (1 × 0.012011 kg/mol)) + (2 × 0.015999 kg/mol))
Engine value: 0.044009 kg/mol. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Inlet molar flow0 mol/s
ṅ_i,in = Σ inlet streams
0 mol/s
Engine value: 0 mol/s. Dimensions checked in SI.
Generated molar flow1 mol/s
generation_i = max(ν_i,0) ξ̇
(1 × 1 mol/s)
Engine value: 1 mol/s. Dimensions checked in SI.
Consumed molar flow0 mol/s
consumption_i = max(−ν_i,0) ξ̇
(0 × 1 mol/s)
Engine value: 0 mol/s. Dimensions checked in SI.
Outlet molar flow1 mol/s
ṅ_i,out = Σ actual outlet streams
(0 mol/s + 1 mol/s)
Engine value: 1 mol/s. Dimensions checked in SI.
Inlet mass flow0 kg/s
ṁ_i,in = ṅ_i,in M_i
(0 mol/s × 0.044009 kg/mol)
Engine value: 0 kg/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Outlet mass flow0.044009 kg/s
ṁ_i,out = ṅ_i,out M_i
((0 mol/s + 1 mol/s) × 0.044009 kg/mol)
Engine value: 0.044009 kg/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Species accounting residual0 mol/s
0 = inlet − outlet + generation − consumption (steady state)
(((0 mol/s − (0 mol/s + 1 mol/s)) + (1 × 1 mol/s)) − (0 × 1 mol/s))
Engine value: 0 mol/s. Dimensions checked in SI.
H2O(g)
Molecular weight18.015 g/mol
M_i = Σ_k a_ki M_k
((0 kg/mol + (2 × 0.001008 kg/mol)) + (1 × 0.015999 kg/mol))
Engine value: 0.018015 kg/mol. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Inlet molar flow0 mol/s
ṅ_i,in = Σ inlet streams
0 mol/s
Engine value: 0 mol/s. Dimensions checked in SI.
Generated molar flow2 mol/s
generation_i = max(ν_i,0) ξ̇
(2 × 1 mol/s)
Engine value: 2 mol/s. Dimensions checked in SI.
Consumed molar flow0 mol/s
consumption_i = max(−ν_i,0) ξ̇
(0 × 1 mol/s)
Engine value: 0 mol/s. Dimensions checked in SI.
Outlet molar flow2 mol/s
ṅ_i,out = Σ actual outlet streams
(0 mol/s + 2 mol/s)
Engine value: 2 mol/s. Dimensions checked in SI.
Inlet mass flow0 kg/s
ṁ_i,in = ṅ_i,in M_i
(0 mol/s × 0.018015 kg/mol)
Engine value: 0 kg/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Outlet mass flow0.03603 kg/s
ṁ_i,out = ṅ_i,out M_i
((0 mol/s + 2 mol/s) × 0.018015 kg/mol)
Engine value: 0.03603 kg/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Species accounting residual0 mol/s
0 = inlet − outlet + generation − consumption (steady state)
(((0 mol/s − (0 mol/s + 2 mol/s)) + (2 × 1 mol/s)) − (0 × 1 mol/s))
Engine value: 0 mol/s. Dimensions checked in SI.
O2(g)
Molecular weight31.998 g/mol
M_i = Σ_k a_ki M_k
(0 kg/mol + (2 × 0.015999 kg/mol))
Engine value: 0.031998 kg/mol. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Inlet molar flow2 mol/s
ṅ_i,in = Σ inlet streams
(0 mol/s + 2 mol/s)
Engine value: 2 mol/s. Dimensions checked in SI.
Generated molar flow0 mol/s
generation_i = max(ν_i,0) ξ̇
(0 × 1 mol/s)
Engine value: 0 mol/s. Dimensions checked in SI.
Consumed molar flow2 mol/s
consumption_i = max(−ν_i,0) ξ̇
(2 × 1 mol/s)
Engine value: 2 mol/s. Dimensions checked in SI.
Outlet molar flow0 mol/s
ṅ_i,out = Σ actual outlet streams
(0 mol/s + 0 mol/s)
Engine value: 0 mol/s. Dimensions checked in SI.
Inlet mass flow0.063996 kg/s
ṁ_i,in = ṅ_i,in M_i
((0 mol/s + 2 mol/s) × 0.031998 kg/mol)
Engine value: 0.063996 kg/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Outlet mass flow0 kg/s
ṁ_i,out = ṅ_i,out M_i
((0 mol/s + 0 mol/s) × 0.031998 kg/mol)
Engine value: 0 kg/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Species accounting residual0 mol/s
0 = inlet − outlet + generation − consumption (steady state)
((((0 mol/s + 2 mol/s) − (0 mol/s + 0 mol/s)) + (0 × 1 mol/s)) − (2 × 1 mol/s))
Engine value: 0 mol/s. Dimensions checked in SI.
Overall mass
PASSInlet mass flow0.080039 kg/s
Σ inlet flows
(0 kg/s + 0.080039 kg/s)
Engine value: 0.080039 kg/s. Dimensions checked in SI.
Outlet mass flow0.080039 kg/s
Σ outlet flows
(0 kg/s + 0.080039 kg/s)
Engine value: 0.080039 kg/s. Dimensions checked in SI.
Signed mass residual · inlet − outlet0 kg/s
r = inlet − outlet
((0 kg/s + 0.080039 kg/s) − (0 kg/s + 0.080039 kg/s))
Engine value: 0 kg/s. Dimensions checked in SI.
Mass closure100 %
Mass closure = ṁ_out / ṁ_in; display as percent
(0.080039 kg/s / 0.080039 kg/s)
Engine value: 1 1. Dimensions checked in SI.
Signed mass error0 %
Signed mass error = (ṁ_in − ṁ_out) / ṁ_in; display as percent
(0 kg/s / 0.080039 kg/s)
Engine value: 0 1. Dimensions checked in SI.
Normalized residual 0 · relative tolerance 1E-10. Zero inlet mass makes percentage closure undefined.
Elemental conservation
C PASS
Inlet element flow1 mol/s
Σ inlet flows
(0 mol/s + 1 mol/s)
Engine value: 1 mol/s. Dimensions checked in SI.
Outlet element flow1 mol/s
Σ outlet flows
(0 mol/s + 1 mol/s)
Engine value: 1 mol/s. Dimensions checked in SI.
Element residual0 mol/s
r = inlet − outlet
((0 mol/s + 1 mol/s) − (0 mol/s + 1 mol/s))
Engine value: 0 mol/s. Dimensions checked in SI.
Normalized residual 0 · tolerance 1E-10.
H PASS
Inlet element flow4 mol/s
Σ inlet flows
(0 mol/s + 4 mol/s)
Engine value: 4 mol/s. Dimensions checked in SI.
Outlet element flow4 mol/s
Σ outlet flows
(0 mol/s + 4 mol/s)
Engine value: 4 mol/s. Dimensions checked in SI.
Element residual0 mol/s
r = inlet − outlet
((0 mol/s + 4 mol/s) − (0 mol/s + 4 mol/s))
Engine value: 0 mol/s. Dimensions checked in SI.
Normalized residual 0 · tolerance 1E-10.
O PASS
Inlet element flow4 mol/s
Σ inlet flows
(0 mol/s + 4 mol/s)
Engine value: 4 mol/s. Dimensions checked in SI.
Outlet element flow4 mol/s
Σ outlet flows
(0 mol/s + 4 mol/s)
Engine value: 4 mol/s. Dimensions checked in SI.
Element residual0 mol/s
r = inlet − outlet
((0 mol/s + 4 mol/s) − (0 mol/s + 4 mol/s))
Engine value: 0 mol/s. Dimensions checked in SI.
Normalized residual 0 · tolerance 1E-10.
Feed conversion & stream totals
Inlet total molar flow3 mol/s
ṅ = Σ_i ṅ_i
((0 mol/s + 1 mol/s) + 2 mol/s)
Engine value: 3 mol/s. Dimensions checked in SI.
Inlet total mass flow0.080039 kg/s
ṁ = Σ_i ṅ_i M_i
((0 kg/s + 0.016043 kg/s) + 0.063996 kg/s)
Engine value: 0.080039 kg/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Inlet mixture molecular weight26.67967 g/mol
M_mix = ṁ / ṅ
(((0 kg/s + 0.016043 kg/s) + 0.063996 kg/s) / ((0 mol/s + 1 mol/s) + 2 mol/s))
Engine value: 0.026679666666666668 kg/mol. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
CH4(g) · molar
Feed-to-molar conversion1 mol/s
ṅ_i = supplied molar flow
1 mol/s
Engine value: 1 mol/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Feed-to-mass conversion0.016043 kg/s
ṁ_i = ṅ_i M_i
(1 mol/s × 0.016043 kg/mol)
Engine value: 0.016042999999999998 kg/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
O2(g) · molar
Feed-to-molar conversion2 mol/s
ṅ_i = supplied molar flow
2 mol/s
Engine value: 2 mol/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Feed-to-mass conversion0.063996 kg/s
ṁ_i = ṅ_i M_i
(2 mol/s × 0.031998 kg/mol)
Engine value: 0.063996 kg/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Outlet total molar flow3 mol/s
ṅ = Σ_i ṅ_i
((((0 mol/s + 0 mol/s) + 1 mol/s) + 2 mol/s) + 0 mol/s)
Engine value: 3 mol/s. Dimensions checked in SI.
Outlet mixture molecular weight26.67967 g/mol
M_mix = ṁ / ṅ
(((((0 kg/s + 0 kg/s) + 0.044009 kg/s) + 0.03603 kg/s) + 0 kg/s) / ((((0 mol/s + 0 mol/s) + 1 mol/s) + 2 mol/s) + 0 mol/s))
Engine value: 0.026679666666666668 kg/mol. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Standard reaction thermodynamics
298.15 K · 1 bar · standard elements. Values are per mole of reaction as written, not per mole of arbitrary feed.
Standard reaction enthalpy, ΔrH°-802.3021 kJ/mol
ΔH°rxn = Σ νi ΔfH°i
((((0 J/mol + (-1 × -74873.1 J/mol)) + (1 × -393522 J/mol)) + (2 × -241826 J/mol)) + (-2 × 0 J/mol))
Engine value: -802302.1000000001 J/mol. Dimensions checked in SI.
Sources: NIST Chemistry WebBook SRD 69: Methane, gas Shomate data; NIST Chemistry WebBook SRD 69: Carbon dioxide, gas Shomate data; NIST Chemistry WebBook SRD 69: Water vapor, gas Shomate data; NIST Chemistry WebBook SRD 69: Oxygen, gas Shomate data
Exothermic at the standard reference state. Actual process heat also depends on inlet and outlet conditions and shaft work.
Standard reaction Gibbs energy, ΔrG°-800.7869 kJ/mol
ΔG°rxn = ΔH°rxn − Tref ΔS°rxn; derived reaction value, not a supplied species formation Gibbs datum
(-802302 J/mol − (298.15 K × -5.082 J/(mol·K)))
Engine value: -800786.9017 J/mol. Dimensions checked in SI.
Sources: NIST Chemistry WebBook SRD 69: Methane, gas Shomate data; NIST Chemistry WebBook SRD 69: Carbon dioxide, gas Shomate data; NIST Chemistry WebBook SRD 69: Water vapor, gas Shomate data; NIST Chemistry WebBook SRD 69: Oxygen, gas Shomate data; NIST-JANAF CH4: standard entropy at 298.15 K; NIST-JANAF CO2: standard entropy at 298.15 K; NIST-JANAF H2O: standard entropy at 298.15 K; NIST-JANAF O2: standard entropy at 298.15 K
Standard reaction entropy, ΔrS°-5.082 J/(mol·K)
ΔS°rxn = Σ νi S°i; absolute standard molar entropies
((((0 J/(mol·K) + (-1 × 186.251 J/(mol·K))) + (1 × 213.795 J/(mol·K))) + (2 × 188.834 J/(mol·K))) + (-2 × 205.147 J/(mol·K)))
Engine value: -5.081999999999994 J/(mol·K). Dimensions checked in SI.
Sources: NIST-JANAF CH4: standard entropy at 298.15 K; NIST-JANAF CO2: standard entropy at 298.15 K; NIST-JANAF H2O: standard entropy at 298.15 K; NIST-JANAF O2: standard entropy at 298.15 K
Gibbs method: standard reaction enthalpy and entropy at the stated reference temperature.
Standard Gibbs energy does not determine conversion, reaction rate or equilibrium composition at the operating conditions.
Energy balance
Q − W + Hin − Hout = 0. Heat is positive into the system; shaft work is positive out. Formation and sensible enthalpy are included once.
Heat removal is required at the specified outlet state.
Inlet enthalpy flow-74.8731 kW
Ḣin = Σ inlet-stream enthalpy flows
(0 W + -74873.1 W)
Engine value: -74873.09999999999 W. Dimensions checked in SI.
Sources: thermo-0; thermo-1; thermo-2; thermo-3
Outlet enthalpy flow-818.3597 kW
Ḣout = Σ outlet-stream enthalpy flows
(0 W + -818360 W)
Engine value: -818359.7282719077 W. Dimensions checked in SI.
Sources: thermo-0; thermo-1; thermo-2; thermo-3
Required heat calculation-743.4866 kW
Q̇required,in = Ḣout − Ḣin + Ẇshaft,out
(((0 W + -818360 W) − (0 W + -74873.1 W)) + 0 W)
Engine value: -743486.6282719077 W. Dimensions checked in SI.
Sources: thermo-0; thermo-1; thermo-2; thermo-3
Formation contribution-802.3021 kW
Formation contribution = Σout ṅi ΔfH°i − Σin ṅi ΔfH°i; for a balanced single reaction this equals ξ̇ ΔH°rxn
(((0 W + (1 mol/s × -393522 J/mol)) + (2 mol/s × -241826 J/mol)) − ((0 W + (1 mol/s × -74873.1 J/mol)) + (2 mol/s × 0 J/mol)))
Engine value: -802302.1 W. Dimensions checked in SI.
Sources: thermo-0; thermo-1; thermo-2; thermo-3
Sensible contribution58.81547 kW
Net sensible contribution = Σout ṅi hs,i − Σin ṅi hs,i
(((0 W + (1 mol/s × 22810.2 J/mol)) + (2 mol/s × 18002.6 J/mol)) − ((0 W + (1 mol/s × 0 J/mol)) + (2 mol/s × 0 J/mol)))
Engine value: 58815.47172809228 W. Dimensions checked in SI.
Sources: thermo-0; thermo-1; thermo-2; thermo-3
These are enthalpy contributions; shaft work is accounted for separately in required heat.
NOT CHECKED Required heat was calculated. No independent heat duty was supplied for closure.
Specific heat-duty bases
Heat per mass of feed-9,289.054 kJ/kg
Specific duty = Q̇_required / ṁ_feed
(-743487 W / 0.080039 kg/s)
Engine value: -9289054.439359657 J/kg. Dimensions checked in SI.
CH4(g)
Heat per mole of limiting reactant fed-743.4866 kJ/mol
Specific duty = Q̇_required / ṅ_limiting,fed
(-743487 W / 1 mol/s)
Engine value: -743486.6282719077 J/mol. Dimensions checked in SI.
Heat per mole of limiting reactant consumed-743.4866 kJ/mol
Specific duty = Q̇_required / ṅ_limiting,consumed
(-743487 W / (1 × 1 mol/s))
Engine value: -743486.6282719077 J/mol. Dimensions checked in SI.
O2(g)
Heat per mole of limiting reactant fed-371.7433 kJ/mol
Specific duty = Q̇_required / ṅ_limiting,fed
(-743487 W / 2 mol/s)
Engine value: -371743.31413595384 J/mol. Dimensions checked in SI.
Heat per mole of limiting reactant consumed-371.7433 kJ/mol
Specific duty = Q̇_required / ṅ_limiting,consumed
(-743487 W / (2 × 1 mol/s))
Engine value: -371743.31413595384 J/mol. Dimensions checked in SI.
A zero denominator has no defined specific duty. Negative values mean removal on the stated basis.
First-principles checks
PASS, WARNING, FAIL and NOT CHECKED describe individual model checks. They do not certify an engineering design.
Methane thermal dataPASS
Properties · Formation enthalpy is reference; Cp is supplied only within its declared range. This checks supplied data, not physical validation.
Oxygen thermal dataPASS
Properties · Formation enthalpy is reference; Cp is supplied only within its declared range. This checks supplied data, not physical validation.
Carbon dioxide thermal dataPASS
Properties · Formation enthalpy is reference; Cp is supplied only within its declared range. This checks supplied data, not physical validation.
Water vapor thermal dataPASS
Properties · Formation enthalpy is reference; Cp is supplied only within its declared range. This checks supplied data, not physical validation.
Specified phase applicabilityWARNING
Assumptions · Phases are supplied, not solved. Gas Cp assumes ideal gases; condensed-phase Cp assumes the specified single phase. No phase stability, latent heat, pressure departure, mixing excess property, equilibrium or dissociation calculation is performed.
C reaction stoichiometryPASS
Stoichiometry · Σ a_ki ν_i; normalized signed residual 0, tolerance 1e-10.
H reaction stoichiometryPASS
Stoichiometry · Σ a_ki ν_i; normalized signed residual 0, tolerance 1e-10.
O reaction stoichiometryPASS
Stoichiometry · Σ a_ki ν_i; normalized signed residual 0, tolerance 1e-10.
Reaction mass consistencyPASS
Stoichiometry · Σ M_i ν_i; normalized signed residual 0. Molecular mass is derived from the same elemental dataset.
Standard reaction enthalpyPASS
Thermodynamics · Complete compatible reference data supplied; this is a reference-state calculation, not an equilibrium prediction.
Standard reaction entropyPASS
Thermodynamics · Complete compatible reference data supplied; this is a reference-state calculation, not an equilibrium prediction.
Standard reaction Gibbs energyPASS
Thermodynamics · Complete compatible reference data supplied; this is a reference-state calculation, not an equilibrium prediction.
Stream dimensionsPASS
Dimensions · All calculated outputs are dimension-checked in canonical SI.
Stoichiometric limiting reactantPASS
Stoichiometry · Limiting species: CH4(g), O2(g); ties use relative tolerance 1e-10. This is an upper bound, not a predicted conversion.
Specified conversion feasibilityPASS
Stoichiometry · Specified X = 1; X_max = 1. No kinetic or equilibrium prediction.
Steady-state mass balancePASS
Conservation · In − out = 0 kg/s; normalized residual 0. Specified-stream consistency only.
C elemental balancePASS
Conservation · In − out = 0 mol atoms/s; normalized residual 0.
H elemental balancePASS
Conservation · In − out = 0 mol atoms/s; normalized residual 0.
O elemental balancePASS
Conservation · In − out = 0 mol atoms/s; normalized residual 0.
Experimental validationNOT CHECKED
Evidence · No measured validation dataset or uncertainty propagation is supplied.
Active stream enthalpy propertiesPASS
Properties · Every positive-flow species has finite, sourced formation-reference enthalpy at the stated temperature; this is property-model consistency, not physical validation.
Thermodynamic applicabilityWARNING
Assumptions · Species phases and composition are supplied. Gas Shomate properties assume ideal gases; no pressure departure, phase change, dissociation, mixing excess enthalpy or uncertainty propagation is calculated.
Active stream enthalpy propertiesPASS
Properties · Every positive-flow species has finite, sourced formation-reference enthalpy at the stated temperature; this is property-model consistency, not physical validation.
Thermodynamic applicabilityWARNING
Assumptions · Species phases and composition are supplied. Gas Shomate properties assume ideal gases; no pressure departure, phase change, dissociation, mixing excess enthalpy or uncertainty propagation is calculated.
Specified-stream energy closureNOT CHECKED
Conservation · Required heat is calculated, but no heat-transfer evidence is supplied to check energy closure. Solving for required heat is not validation.
Formation and sensible energy contributionsPASS
Thermodynamics · These two contributions sum to Ḣout−Ḣin. Add shaft work out to obtain required heat; do not add reaction heat a second time.
Energy contribution consistencyPASS
Numerical precision · Formation + sensible + shaft work = -743486.6282719077 W; agrees with stream-enthalpy duty at relative tolerance 1e-10, scaled by individual contribution magnitudes.
Reactor input reference
Calculated values for manual review and transfer. This does not update the Reactor Calculator or a Project Builder record.
Outlet molar flow3 mol/s
ṅ = Σ_i ṅ_i
((((0 mol/s + 0 mol/s) + 1 mol/s) + 2 mol/s) + 0 mol/s)
Engine value: 3 mol/s. Dimensions checked in SI.
Outlet mass flow0.080039 kg/s
ṁ = Σ_i ṅ_i M_i
((((0 kg/s + 0 kg/s) + 0.044009 kg/s) + 0.03603 kg/s) + 0 kg/s)
Engine value: 0.080039 kg/s. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Outlet molecular weight26.67967 g/mol
M_mix = ṁ / ṅ
(((((0 kg/s + 0 kg/s) + 0.044009 kg/s) + 0.03603 kg/s) + 0 kg/s) / ((((0 mol/s + 0 mol/s) + 1 mol/s) + 2 mol/s) + 0 mol/s))
Engine value: 0.026679666666666668 kg/mol. Dimensions checked in SI.
Sources: CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
Outlet ideal-gas volume flow0.1995471 m³/s
V̇_ideal gas = ṅ R T / P at the displayed outlet conditions
(((3 mol/s × 8.31446 J/(mol·K)) × 800 K) / 100000 Pa)
Engine value: 0.19954710283567775 m³/s. Dimensions checked in SI.
Outlet state: 800 K · 1 bar absolute. Optional manual transfer quantities at the displayed outlet state. These do not solve a reacting bed, pressure drop or coupled reactor model. Ideal-gas volume is withheld for active non-gas species or missing conditions.
Assumptions, sources & limits
WARNING Preliminary engineering calculation. Results have not been experimentally validated and are not design certification.
- Steady state: no mass, elemental, or energy accumulation; no nuclear transformations.
- One prescribed reaction and a user-specified feasible conversion or extent; no predicted kinetics, selectivity, or equilibrium.
- Energy uses compatible formation-enthalpy reference states and single-phase property models; kinetic and potential energy changes are neglected.
- Heat is positive into the control volume and shaft work is positive out. Formation enthalpy already accounts for reaction energy.
- Conservation checks are consistency checks for specified/modelled streams, not experimental or design validation.
- A single mixed feed and one prescribed reaction are evaluated. Conversion or extent is an input, not a prediction.
- Species phases and identities are supplied. Formula composition does not distinguish isomers or verify a physical phase.
- No phase equilibrium, flash, latent-heat path, dissociation, real-gas correction or mixture excess enthalpy is solved.
- Property and numerical tolerances do not represent measurement uncertainty or design certification.
- Reaction quantities are per mole of reaction exactly as written, at 298.15 K and 1 bar.
- Standard ΔG° does not establish actual reactor equilibrium at other temperatures, pressures, compositions or activities.
- Species phases and chemical identities are explicitly supplied. Source rounding and uncertainty are not propagated.
- Feed rates are canonical SI; molecular weights use the selected atomic dataset. No standard-volume convention is assumed.
- Species identities and elemental counts describe neutral molecules; isotope, ion, and nuclear transformations are outside this model.
- Component flows determine reported totals. Input fractions are not renormalized.
- Steady flow: energy accumulation is explicitly assumed zero; kinetic and potential energy changes are neglected.
- Heat is positive into the system; shaft work is positive out. Flow work is included in enthalpy.
- Stream enthalpies include formation enthalpies; reaction heat is not added again as an independent generation term.
- Gas Shomate properties use an ideal-gas model at supplied composition; no pressure departure, phase equilibrium, dissociation or excess enthalpy is solved.
- Property integration paths are range-checked. Continuous Cp integration removes fitted enthalpy offset jumps while preserving published Cp coefficients. Source uncertainty is not propagated.
- One mixed inlet and one calculated outlet. Prescribed reaction progress; no kinetic or equilibrium prediction.
- Gas, liquid and solid phase labels remain fixed. No flash, condensation, latent heat or multiphase equilibrium is calculated.
- Manual thermodynamic values require a documented source, consistent identity and the stated reference state. A property-data gap is never filled with an invented value.
- Reported precision reflects numerical formatting, not physical measurement accuracy.
Property & method references
- CIAAW Abridged Standard Atomic Weights 2024
Based on Atomic Weights 2021 with CIAAW 2024 revisions. One fixed abridged convention is used for all molecular masses; isotopic variation is not propagated.
- NIST Chemistry WebBook SRD 69: Nitrogen, gas Shomate data
Chase, NIST-JANAF Thermochemical Tables, fourth edition, 1998. Reviewed March 1977; parameter fit January 2009. Reference 298.15 K, 1 bar; source Cp in J/(mol K), enthalpy constants in kJ/mol. Finite coefficient digits do not establish property uncertainty.
- NIST Chemistry WebBook SRD 69: Oxygen, gas Shomate data
Chase, NIST-JANAF Thermochemical Tables, fourth edition, 1998. Reviewed March 1977; parameter fit January 2009. Reference 298.15 K, 1 bar; source Cp in J/(mol K), enthalpy constants in kJ/mol. Finite coefficient digits do not establish property uncertainty.
- NIST Chemistry WebBook SRD 69: Hydrogen, gas Shomate data
Chase, NIST-JANAF Thermochemical Tables, fourth edition, 1998. Reviewed March 1977; parameter fit October 2001. Reference 298.15 K, 1 bar; source Cp in J/(mol K), enthalpy constants in kJ/mol. Finite coefficient digits do not establish property uncertainty.
- NIST Chemistry WebBook SRD 69: Water vapor, gas Shomate data
Chase, NIST-JANAF Thermochemical Tables, fourth edition, 1998. Reviewed March 1979. Gas Cp fit starts at 500 K; formation reference remains 298.15 K. Reference 298.15 K, 1 bar; source Cp in J/(mol K), enthalpy constants in kJ/mol. Finite coefficient digits do not establish property uncertainty.
- NIST Chemistry WebBook SRD 69: Methane, gas Shomate data
Chase, NIST-JANAF Thermochemical Tables, fourth edition, 1998. Reviewed March 1961. Reference 298.15 K, 1 bar; source Cp in J/(mol K), enthalpy constants in kJ/mol. Finite coefficient digits do not establish property uncertainty.
- NIST Chemistry WebBook SRD 69: Carbon monoxide, gas Shomate data
Chase, NIST-JANAF Thermochemical Tables, fourth edition, 1998. Reviewed September 1965. Reference 298.15 K, 1 bar; source Cp in J/(mol K), enthalpy constants in kJ/mol. Finite coefficient digits do not establish property uncertainty.
- NIST Chemistry WebBook SRD 69: Carbon dioxide, gas Shomate data
Chase, NIST-JANAF Thermochemical Tables, fourth edition, 1998. Reviewed September 1965. Reference 298.15 K, 1 bar; source Cp in J/(mol K), enthalpy constants in kJ/mol. Finite coefficient digits do not establish property uncertainty.
- NIST WebBook: ammonia gas Shomate data
Chase 1998, reviewed June 1977. 298.15 K, 1 bar. Small attributed coefficient/reference selection; not an open license to the SRD compilation.
- NIST WebBook: liquid-water Shomate data
Chase 1998, reviewed March 1979. 298–500 K correlation for the specified liquid phase; does not establish phase stability. H constant −285.8304 kJ/mol.
- NIST WebBook: n-octane liquid formation enthalpy
Good 1972: −250.3 ± 1.8 kJ/mol at 298.15 K. n-Octane CAS 111-65-9, not an arbitrary C8H18 isomer. Nominal source standard pressure 1 atm; condensed-phase 1 atm-to-1 bar enthalpy correction neglected, well below source uncertainty. No Cp is inferred from single-temperature measurements.
- NIST WebBook: n-octane gas formation enthalpy
NIST computed −208.7 kJ/mol from Good 1972 liquid formation enthalpy and Prosen/Rossini 1945 vaporization enthalpy. Ideal-gas H is pressure-independent. CAS 111-65-9; no Cp fit is invented from discrete data.
- NIST-JANAF N2: standard entropy at 298.15 K
Chase 1998, explicitly 298.15 K and 0.1 MPa. Absolute standard molar entropy, not entropy of formation; table precision is not a propagated uncertainty estimate.
- NIST-JANAF O2: standard entropy at 298.15 K
Chase 1998, explicitly 298.15 K and 0.1 MPa. Absolute standard molar entropy, not entropy of formation; table precision is not a propagated uncertainty estimate.
- NIST-JANAF H2: standard entropy at 298.15 K
Chase 1998, explicitly 298.15 K and 0.1 MPa. Absolute standard molar entropy, not entropy of formation; table precision is not a propagated uncertainty estimate.
- NIST-JANAF H2O: standard entropy at 298.15 K
Chase 1998, explicitly 298.15 K and 0.1 MPa. Absolute standard molar entropy, not entropy of formation; table precision is not a propagated uncertainty estimate.
- NIST-JANAF CH4: standard entropy at 298.15 K
Chase 1998, explicitly 298.15 K and 0.1 MPa. Absolute standard molar entropy, not entropy of formation; table precision is not a propagated uncertainty estimate.
- NIST-JANAF CO: standard entropy at 298.15 K
Chase 1998, explicitly 298.15 K and 0.1 MPa. Absolute standard molar entropy, not entropy of formation; table precision is not a propagated uncertainty estimate.
- NIST-JANAF CO2: standard entropy at 298.15 K
Chase 1998, explicitly 298.15 K and 0.1 MPa. Absolute standard molar entropy, not entropy of formation; table precision is not a propagated uncertainty estimate.
- NIST-JANAF NH3: standard entropy at 298.15 K
Chase 1998, explicitly 298.15 K and 0.1 MPa. Absolute standard molar entropy, not entropy of formation; table precision is not a propagated uncertainty estimate.
- NIST-JANAF waterLiquid: standard entropy at 298.15 K
Chase 1998, explicitly 298.15 K and 0.1 MPa. Absolute standard molar entropy, not entropy of formation; table precision is not a propagated uncertainty estimate.
- CIAAW Abridged Standard Atomic Weights 2024 — © CIAAW/IUPAC 2024
84 numeric abridged standard atomic weights for normal isotopic composition, converted from g/mol to kg/mol. © CIAAW/IUPAC 2024. Stated source uncertainties retained; no uncertainty propagation is performed. Elements without a standard atomic weight are unsupported.
- Methane: compiled enthalpy inputs
Standard-elements reference: 298.15 K, 1 bar. Hf: NIST Chemistry WebBook SRD 69: Methane, gas Shomate data. Cp: NIST Chemistry WebBook SRD 69: Methane, gas Shomate data. Individual property provenance remains in the resolved record.
- Oxygen: compiled enthalpy inputs
Standard-elements reference: 298.15 K, 1 bar. Hf: NIST Chemistry WebBook SRD 69: Oxygen, gas Shomate data. Cp: NIST Chemistry WebBook SRD 69: Oxygen, gas Shomate data. Individual property provenance remains in the resolved record.
- Carbon dioxide: compiled enthalpy inputs
Standard-elements reference: 298.15 K, 1 bar. Hf: NIST Chemistry WebBook SRD 69: Carbon dioxide, gas Shomate data. Cp: NIST Chemistry WebBook SRD 69: Carbon dioxide, gas Shomate data. Individual property provenance remains in the resolved record.
- Water vapor: compiled enthalpy inputs
Standard-elements reference: 298.15 K, 1 bar. Hf: NIST Chemistry WebBook SRD 69: Water vapor, gas Shomate data. Cp: NIST Chemistry WebBook SRD 69: Water vapor, gas Shomate data. Individual property provenance remains in the resolved record.
Engine 0.3.0 · Dataset universal-properties-2026-09-07.v1
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