Chemical Reactions (chemicals.reaction)

This module contains lookup functions enthalpies and standard entropies of formation. Lookup functions are availa for the liquid, solid, and gas states. A compound may be in more than one lookup function.

For reporting bugs, adding feature requests, or submitting pull requests, please use the GitHub issue tracker.

Solid Heat of Formation

chemicals.reaction.Hfs(CASRN, method=None)[source]

This function handles the retrieval of a chemical’s solid/crystaline standard phase heat of formation. The lookup is based on CASRNs. Will automatically select a data source to use if no method is provided; returns None if the data is not available.

Parameters
CASRNstr

CASRN [-]

Returns
Hfsfloat

Solid standard-state heat of formation, [J/mol]

Other Parameters
methodstr, optional

A string for the method name to use, as defined by constants in Hfs_methods

See also

Hfs_methods

Notes

Sources are:

  • ‘CRC’, from the CRC handbook (1360 values) [1]

  • ‘WEBBOOK’ (2000 values) [2]

References

1

Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of Chemistry and Physics. [Boca Raton, FL]: CRC press, 2014.

2

Shen, V.K., Siderius, D.W., Krekelberg, W.P., and Hatch, H.W., Eds., NIST WebBook, NIST, http://doi.org/10.18434/T4M88Q

Examples

>>> Hfs('101-81-5') # Diphenylmethane
71500.0
chemicals.reaction.Hfs_methods(CASRN)[source]

Return all methods available to obtain the solid-phase heat of formation for the desired chemical.

Parameters
CASRNstr

CASRN, [-]

Returns
methodslist[str]

Methods which can be used to obtain the Hfs with the given inputs.

See also

Hfs
chemicals.reaction.Hfs_all_methods = ('CRC', 'WEBBOOK')

Tuple of method name keys. See the Hfs for the actual references

Liquid Heat of Formation

chemicals.reaction.Hfl(CASRN, method=None)[source]

This function handles the retrieval of a chemical’s liquid standard phase heat of formation. The lookup is based on CASRNs. Will automatically select a data source to use if no method is provided; returns None if the data is not available.

Parameters
CASRNstr

CASRN [-]

Returns
Hflfloat

Liquid standard-state heat of formation, [J/mol]

Other Parameters
methodstr, optional

A string for the method name to use, as defined in the variable, Hfl_all_methods.

See also

Hfl_methods

Notes

Sources are:

  • ‘ATCT_L’, the Active Thermochemical Tables version 1.112. [1]

  • ‘CRC’, from the CRC handbook (1360 values) [2]

  • ‘WEBBOOK’ (2000 values) [3]

References

1

Ruscic, Branko, Reinhardt E. Pinzon, Gregor von Laszewski, Deepti Kodeboyina, Alexander Burcat, David Leahy, David Montoy, and Albert F. Wagner. “Active Thermochemical Tables: Thermochemistry for the 21st Century.” Journal of Physics: Conference Series 16, no. 1 (January 1, 2005): 561. doi:10.1088/1742-6596/16/1/078.

2

Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of Chemistry and Physics. [Boca Raton, FL]: CRC press, 2014.

3

Shen, V.K., Siderius, D.W., Krekelberg, W.P., and Hatch, H.W., Eds., NIST WebBook, NIST, http://doi.org/10.18434/T4M88Q

Examples

>>> Hfl('67-56-1')
-238400.0
chemicals.reaction.Hfl_methods(CASRN)[source]

Return all methods available to obtain the standard liquid-state heat of formation for the desired chemical.

Parameters
CASRNstr

CASRN, [-]

Returns
methodslist[str]

Methods which can be used to obtain the Hfl with the given inputs.

See also

Hfl
chemicals.reaction.Hfl_all_methods = ('ATCT_L', 'CRC', 'WEBBOOK', 'JANAF')

Tuple of method name keys. See the Hfl for the actual references

Gas Heat of Formation

chemicals.reaction.Hfg(CASRN, method=None)[source]

This function handles the retrieval of a chemical’s gas heat of formation. Lookup is based on CASRNs. Will automatically select a data source to use if no method is provided; returns None if the data is not available.

Parameters
CASRNstr

CASRN [-]

Returns
Hfgfloat

Ideal gas phase heat of formation, [J/mol]

Other Parameters
methodstr, optional

A string for the method name to use, as defined by constants in Hfg_methods

See also

Hfg_methods

Notes

Function has data for approximately 8700 chemicals. Sources are:

  • ‘ATCT_G’, the Active Thermochemical Tables version 1.112 (600 values) [1]

  • ‘TRC’, from a 1994 compilation (1750 values) [2]

  • ‘CRC’, from the CRC handbook (1360 values) [3]

  • ‘WEBBOOK’, a NIST resource [6] containing mostly experimental and averaged values

  • ‘JANAF’, the 1998 JANAF values online

  • ‘JOBACK’, an estimation method for organic substances in [5]

  • ‘YAWS’, a large compillation of values, mostly estimated (5000 values) [4]

‘TRC’ data may have come from computational procedures, for example petane is off by 30%.

References

1

Ruscic, Branko, Reinhardt E. Pinzon, Gregor von Laszewski, Deepti Kodeboyina, Alexander Burcat, David Leahy, David Montoy, and Albert F. Wagner. “Active Thermochemical Tables: Thermochemistry for the 21st Century.” Journal of Physics: Conference Series 16, no. 1 (January 1, 2005): 561. doi:10.1088/1742-6596/16/1/078.

2

Frenkel`, M. L, Texas Engineering Experiment Station, and Thermodynamics Research Center. Thermodynamics of Organic Compounds in the Gas State. College Station, Tex.: Thermodynamics Research Center, 1994.

3

Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of Chemistry and Physics. [Boca Raton, FL]: CRC press, 2014.

4

Yaws, Carl L. Thermophysical Properties of Chemicals and Hydrocarbons, Second Edition. Amsterdam Boston: Gulf Professional Publishing, 2014.

5

Joback, K.G., and R.C. Reid. “Estimation of Pure-Component Properties from Group-Contributions.” Chemical Engineering Communications 57, no. 1-6 (July 1, 1987): 233-43. doi:10.1080/00986448708960487.

6

Shen, V.K., Siderius, D.W., Krekelberg, W.P., and Hatch, H.W., Eds., NIST WebBook, NIST, http://doi.org/10.18434/T4M88Q

Examples

>>> Hfg('67-56-1')
-200700.0
>>> Hfg('67-56-1', method='YAWS')
-200900.0
>>> Hfg('67-56-1', method='CRC')
-201000.0
>>> Hfg('67-56-1', method='TRC')
-190100.0
chemicals.reaction.Hfg_methods(CASRN)[source]

Return all methods available to obtain the gas phase heat of formation for the desired chemical.

Parameters
CASRNstr

CASRN, [-]

Returns
methodslist[str]

Methods which can be used to obtain the Hfg with the given inputs.

See also

Hfg
chemicals.reaction.Hfg_all_methods = ('ATCT_G', 'TRC', 'CRC', 'WEBBOOK', 'JANAF', 'YAWS', 'JOBACK')

Tuple of method name keys. See the Hfg for the actual references

Solid Absolute Entropy

chemicals.reaction.S0s(CASRN, method=None)[source]

This function handles the retrieval of a chemical’s absolute entropy at a reference temperature of 298.15 K and pressure of 1 bar, in the solid state. Lookup is based on CASRNs. Will automatically select a data source to use if no method is provided; returns None if the data is not available.

Parameters
CASRNstr

CASRN [-]

Returns
S0sfloat

Ideal gas standard absolute entropy of compound, [J/mol/K]

Other Parameters
methodstr, optional

A string for the method name to use, as defined by constants in S0s_all_methods.

See also

S0s_methods

Notes

Sources are:

  • ‘CRC’ [1] from the CRC handbook (1360 values)

  • ‘WEBBOOK’, a NIST resource [2] containing mostly experimental and averaged values

References

1

Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of Chemistry and Physics. [Boca Raton, FL]: CRC press, 2014.

2

Shen, V.K., Siderius, D.W., Krekelberg, W.P., and Hatch, H.W., Eds., NIST WebBook, NIST, http://doi.org/10.18434/T4M88Q

Examples

>>> S0s('7439-93-2') # Lithium
29.1
chemicals.reaction.S0s_methods(CASRN)[source]

Return all methods available to obtain the absolute entropy of the compound in the solid phase for the desired chemical.

Parameters
CASRNstr

CASRN, [-]

Returns
methodslist[str]

Methods which can be used to obtain the S0s with the given inputs.

See also

S0s
chemicals.reaction.S0s_all_methods = ('CRC', 'WEBBOOK')

Tuple of method name keys. See the S0s for the actual references

Liquid Absolute Entropy

chemicals.reaction.S0l(CASRN, method=None)[source]

This function handles the retrieval of a chemical’s absolute entropy at a reference temperature of 298.15 K and pressure of 1 bar, in the liquid state.

Lookup is based on CASRNs. Will automatically select a data source to use if no method is provided; returns None if the data is not available.

Parameters
CASRNstr

CASRN [-]

Returns
S0lfloat

Ideal gas standard absolute entropy of compound, [J/mol/K]

Other Parameters
methodstr, optional

A string for the method name to use, as defined in the variable, S0l_all_methods.

See also

S0l_methods

Notes

Sources are:

  • ‘CRC’, from the CRC handbook

References

1

Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of Chemistry and Physics. [Boca Raton, FL]: CRC press, 2014.

Examples

>>> S0l('7439-97-6') # Mercury
75.9
chemicals.reaction.S0l_methods(CASRN)[source]

Return all methods available to obtain the absolute entropy for the desired chemical.

Parameters
CASRNstr

CASRN, [-]

Returns
methodslist[str]

Methods which can be used to obtain the S0l with the given inputs.

See also

S0l
chemicals.reaction.S0l_all_methods = ('CRC', 'WEBBOOK', 'JANAF')

Tuple of method name keys. See the S0l for the actual references

Gas Absolute Entropy

chemicals.reaction.S0g(CASRN, method=None)[source]

This function handles the retrieval of a chemical’s absolute entropy at a reference temperature of 298.15 K and pressure of 1 bar, in the ideal gas state.

Lookup is based on CASRNs. Will automatically select a data source to use if no method is provided; returns None if the data is not available.

Parameters
CASRNstr

CASRN [-]

Returns
S0gfloat

Ideal gas standard absolute entropy of compound, [J/mol/K]

Other Parameters
methodstr, optional

A string for the method name to use, as defined in the variable, S0g_all_methods

See also

S0g_methods

Notes

Function has data for approximately 5400 chemicals. Sources are:

  • ‘CRC’, from the CRC handbook (520 values)

  • ‘YAWS’, a large compillation of values, mostly estimated (4890 values)

  • ‘WEBBOOK’, a NIST resource [3] containing mostly experimental and averaged values

References

1

Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of Chemistry and Physics. [Boca Raton, FL]: CRC press, 2014.

2

Yaws, Carl L. Thermophysical Properties of Chemicals and Hydrocarbons, Second Edition. Amsterdam Boston: Gulf Professional Publishing, 2014.

3

Shen, V.K., Siderius, D.W., Krekelberg, W.P., and Hatch, H.W., Eds., NIST WebBook, NIST, http://doi.org/10.18434/T4M88Q

Examples

>>> S0g('67-56-1')
239.9
>>> S0g('67-56-1', method='YAWS')
239.88
chemicals.reaction.S0g_methods(CASRN)[source]

Return all methods available to obtain the S0g for the desired chemical.

Parameters
CASRNstr

CASRN, [-]

Returns
methodslist[str]

Methods which can be used to obtain the S0g with the given inputs.

See also

S0g
chemicals.reaction.S0g_all_methods = ('CRC', 'WEBBOOK', 'JANAF', 'YAWS')

Tuple of method name keys. See the S0g for the actual references

Utility Functions

chemicals.reaction.Gibbs_formation(dHf, S0_abs, dHfs_std, S0_abs_elements, coeffs_elements, T_ref=298.15)[source]

This function calculates the Gibbs free energy of formation of a compound, from its constituent elements.

The calculated value will be for a “standard-state” value if dHf and S0_abs are provided in the standard state; or it will be in an “ideal gas” basis if they are both for an ideal gas. For compounds which are gases at STP, the two values are the same.

Parameters
dHffloat

Molar enthalpy of formation of the created compound, [J/mol]

S0_absfloat

Absolute molar entropy of the created compound at the reference temperature, [J/mol/K]

dHfs_stdlist[float]

List of standard molar enthalpies of formation of all elements used in the formation of the created compound, [J/mol]

S0_abs_elementslist[float]

List of standard absolute molar entropies at the reference temperature of all elements used in the formation of the created compound, [J/mol/K]

coeffs_elementslist[float]

List of coefficients for each compound (i.e. 1 for C, 2 for H2 if the target is methane), in the same order as dHfs_std and S0_abs_elements, [-]

T_reffloat, optional

The standard state temperature, default 298.15 K; few values are tabulated at other temperatures, [-]

Returns
dGffloat

Gibbs free energy of formation for the created compound, [J/mol]

Notes

Be careful for elements like Bromine - is the tabulated value for Br2 or Br?

References

1

“Standard Gibbs Free Energy of Formation Calculations Chemistry Tutorial.” Accessed March, 2019. https://www.ausetute.com.au/gibbsform.html.

Examples

Calculate the standard-state Gibbs free energy of formation for water, using water’s standard state heat of formation and absolute entropy at 298.15 K:

>>> Gibbs_formation(-285830, 69.91,  [0, 0], [130.571, 205.147], [1, .5])
-237161.633825

Calculate the ideal-gas state Gibbs free energy of formation for water, using water’s ideal-gas state heat of formation and absolute entropy at 298.15 K as a gas:

>>> Gibbs_formation(-241818, 188.825,  [0, 0], [130.571, 205.147], [1, .5])
-228604.141075

Calculate the Gibbs free energy of formation for CBrF3 (it is a gas at STP, so its standard-state and ideal-gas state values are the same) at 298.15 K:

>>> Gibbs_formation(-648980, 297.713, [0, 0, 0], [5.74, 152.206, 202.789], [1, .5, 1.5])
-622649.329975

Note in the above calculation that the Bromine’s S0 and Hf are for Br2; and that the value for Bromine as a liquid, which is its standard state, is used.

chemicals.reaction.entropy_formation(Hf, Gf, T_ref=298.15)[source]

This function calculates the entropy of formation of a compound, from its constituent elements.

The calculated value will be for a “standard-state” value if Hf and Gf are provided in the standard state; or it will be in an “ideal gas” basis if they are both for an ideal gas. For compounds which are gases at STP, the two values are the same.

Parameters
Hffloat

Molar enthalpy of formation of the compound, [J/mol]

Gffloat

Molar Gibbs free energy of formation of the compound, [J/mol]

T_reffloat, optional

The standard state temperature, default 298.15 K; few values are tabulated at other temperatures, [-]

Returns
S0float

Entropy of formation of the compound, [J/mol/K]

Examples

Entropy of formation of methane:

>>> entropy_formation(Hf=-74520, Gf=-50490)
-80.59701492537314

Entropy of formation of water in ideal gas state:

>>> entropy_formation(Hf=-241818, Gf=-228572)
-44.427301693778304
chemicals.reaction.Hf_basis_converter(Hvapm, Hf_liq=None, Hf_gas=None)[source]

This function converts a liquid or gas enthalpy of formation to the other. This is useful, as thermodynamic packages often work with ideal- gas as the reference state and require ideal-gas enthalpies of formation.

Parameters
Hvapmfloat

Molar enthalpy of vaporization of compound at 298.15 K or (unlikely) the reference temperature, [J/mol]

Hf_liqfloat, optional

Enthalpy of formation of the compound in its liquid state, [J/mol]

Hf_gasfloat, optional

Enthalpy of formation of the compound in its ideal-gas state, [J/mol]

Returns
Hf_calcfloat, optional

Enthalpy of formation of the compound in the other state to the one provided, [J/mol]

Examples

Calculate the ideal-gas enthalpy of formation for water, from its standard- state (liquid) value:

>>> Hf_basis_converter(44018, Hf_liq=-285830)
-241812

Calculate the standard-state (liquid) enthalpy of formation for water, from its ideal-gas value:

>>> Hf_basis_converter(44018, Hf_gas=-241812)
-285830

Chemical Reactions

chemicals.reaction.balance_stoichiometry(matrix, rounding=9, allow_fractional=False)[source]

This function balances a chemical reaction.

Parameters
matrixlist[list[float]]
Chemical reaction matrix for further processing; rows contain element

counts of each compound, and the columns represent each chemical, [-]

roundingint

Roughly the number of digits of rounding to apply to the answer. As matrix routines are used, there is some noise; if this number is too high, the coefficients may become very large numberes, which are still in a correct ratio to each other, but are extremely ugly, [-]

allow_fractionalbool

Whether or not to allow the answers to be fractions, or to force them to integers. Setting this to True speeds up the calculation, and allows setting rounding arbitrarily high, [-]

Returns
coefficientslist[float]

Balanced coefficients; all numbers are positive, [-]

Notes

Balance the reaction 4 NH3 + 5 O2 = 4 NO + 6 H2O, without knowing the coefficients:

>>> matrix = stoichiometric_matrix([{'N': 1, 'H': 3}, {'O': 2}, {'N': 1, 'O': 1}, {'H': 2, 'O': 1}], [True, True, False, False])
>>> matrix
[[3, 0, 0, -2], [1, 0, -1, 0], [0, 2, -1, -1]]
>>> balance_stoichiometry(matrix)
[4.0, 5.0, 4.0, 6.0]
>>> balance_stoichiometry(matrix, allow_fractional=True)
[1.0, 1.25, 1.0, 1.5]

The behavior of this function for inputs which do not have a unique solution is undefined.

This algorithm may suffer from floating point issues. If you believe there is an error in the result, please report your reaction to the developers. This function has a comprehensive test suite and extra test cases can be added to it.

References

1

Sen, S. K., Hans Agarwal, and Sagar Sen. “Chemical Equation Balancing: An Integer Programming Approach.” Mathematical and Computer Modelling 44, no. 7 (October 1, 2006): 678-91. https://doi.org/10.1016/j.mcm.2006.02.004.

2

URAVNOTE, NOVOODKRITI PARADOKSI V. TEORIJI, and ENJA KEMIJSKIH REAKCIJ. “New Discovered Paradoxes in Theory of Balancing Chemical Reactions.” Materiali in Tehnologije 45, no. 6 (2011): 503-22.

3

Risteski, Ice B. “A New Approach to Balancing Chemical Equations.” SIAM Problems & Solutions, 2007, 1-10.

4

Smith, William R., and Ronald W. Missen. “Using Mathematica and Maple To Obtain Chemical Equations.” Journal of Chemical Education 74, no. 11 (November 1, 1997): 1369. https://doi.org/10.1021/ed074p1369.

chemicals.reaction.stoichiometric_matrix(atomss, reactants)[source]

This function calculates a stoichiometric matrix of reactants and stoichiometric matrix, as required by a solver to compute the reation coefficients.

Parameters
atomsslist[dict[(str, float)]]

A list of dictionaties of (element, element_count) pairs for each chemical, [-]

reactantslist[bool]

List of booleans indicating whether each chemical is a reactant (True) or a product (False), [-]

Returns
matrixlist[list[float]]
Chemical reaction matrix for further processing; rows contain element

counts of each compound, and the columns represent each chemical, [-]

Notes

The rows of the matrix contain the element counts of each compound, and the columns represent each chemical.

References

1

Sen, S. K., Hans Agarwal, and Sagar Sen. “Chemical Equation Balancing: An Integer Programming Approach.” Mathematical and Computer Modelling 44, no. 7 (October 1, 2006): 678-91. https://doi.org/10.1016/j.mcm.2006.02.004.

2

URAVNOTE, NOVOODKRITI PARADOKSI V. TEORIJI, and ENJA KEMIJSKIH REAKCIJ. “New Discovered Paradoxes in Theory of Balancing Chemical Reactions.” Materiali in Tehnologije 45, no. 6 (2011): 503-22.

Examples

MgO2 -> Mg + 1/2 O2 (k=1)

>>> stoichiometric_matrix([{'Mg': 1, 'O': 1}, {'Mg': 1}, {'O': 2}], [True, False, False])
[[1, -1, 0], [1, 0, -2]]

Cl2 + propylene -> allyl chloride + HCl

>>> stoichiometric_matrix([{'Cl': 2}, {'C': 3, 'H': 6}, {'C': 3, 'Cl': 1, 'H': 5}, {'Cl': 1, 'H': 1}], [True, True, False, False, False])
[[0, 3, -3, 0], [2, 0, -1, -1], [0, 6, -5, -1]]

Al + 4HNO3 -> Al(NO3)3 + NO + 2H2O (k=1)

>>> stoichiometric_matrix([{'Al': 1}, {'H': 1, 'N': 1, 'O': 3}, {'Al': 1, 'N': 3, 'O': 9}, {'N': 1, 'O': 1}, {'H': 2, 'O': 1}], [True, True, False, False, False])
[[1, 0, -1, 0, 0], [0, 1, 0, 0, -2], [0, 1, -3, -1, 0], [0, 3, -9, -1, -1]]

4Fe + 3O2 -> 2(Fe2O3) (k=2)

>>> stoichiometric_matrix([{'Fe': 1}, {'O': 2}, {'Fe':2, 'O': 3}], [True, True, False])
[[1, 0, -2], [0, 2, -3]]

4NH3 + 5O2 -> 4NO + 6(H2O) (k=4)

>>> stoichiometric_matrix([{'N': 1, 'H': 3}, {'O': 2}, {'N': 1, 'O': 1}, {'H': 2, 'O': 1}], [True, True, False, False])
[[3, 0, 0, -2], [1, 0, -1, 0], [0, 2, -1, -1]]

No unique solution: C2H5NO2 + C3H7NO3 + 2C6H14N4O2 + 3C5H9NO2 + 2C9H11NO2 -> 8H2O + C50H73N15O11

>>> stoichiometric_matrix([{'C': 2, 'H': 5, 'N': 1, 'O': 2}, {'C': 3, 'H': 7, 'N': 1, 'O': 3}, {'C': 6, 'H': 14, 'N': 4, 'O': 2}, {'C': 5, 'H': 9, 'N': 1, 'O': 2}, {'C': 9, 'H': 11, 'N': 1, 'O': 2}, {'H': 2, 'O': 1}, {'C': 50, 'H': 73, 'N': 15, 'O': 11}], [True, True, True, True, True, False, False])
[[2, 3, 6, 5, 9, 0, -50], [5, 7, 14, 9, 11, -2, -73], [1, 1, 4, 1, 1, 0, -15], [2, 3, 2, 2, 2, -1, -11]]
chemicals.reaction.stoichiometry_mass_to_molar(mass_coefficients, MWs)[source]

This function translates mass stoichiometric coefficients into the more commonly used mole-based stoichiometric coefficients.

Parameters
mass_coefficientslist[float]

Mass-based balanced coefficients; all numbers are positive, [-]

MWslist[float]

Molecular weights of all species in reaction ordered in the same way as the coefficients, [g/mol]

Returns
coefficientslist[float]

Molar balanced stoichiometric coefficients; all numbers are positive, [-]

Notes

>>> stoichiometry_mass_to_molar([68.12208, 159.994, 120.0244, 108.09168], [17.03052, 31.9988, 30.0061, 18.01528])
[4.0, 5.0, 4.0, 6.0]
chemicals.reaction.stoichiometry_molar_to_mass(coefficients, MWs)[source]

This function translates molar stoichiometric coefficients (most commonly used) into less commonly used mass-based stoichiometric coefficients.

Parameters
coefficientslist[float]

Molar balanced stoichiometric coefficients; all numbers are positive, [-]

MWslist[float]

Molecular weights of all species in reaction ordered in the same way as the coefficients, [g/mol]

Returns
mass_coefficientslist[float]

Mass-based balanced coefficients; all numbers are positive, [-]

Notes

Note that mass-based reactions are usually not normalized to integers. Mass-based coefficients are used with components that don’t have well defined formulas.

Calculate the mass based coefficients for the reaction 4 NH3 + 5 O2 = 4 NO + 6 H2O:

>>> matrix = stoichiometric_matrix([{'N': 1, 'H': 3}, {'O': 2}, {'N': 1, 'O': 1}, {'H': 2, 'O': 1}], [True, True, False, False])
>>> coeffs = balance_stoichiometry(matrix)
>>> stoichiometry_molar_to_mass(coeffs, [17.03052, 31.9988, 30.0061, 18.01528])
[68.12208, 159.994, 120.0244, 108.09168]
chemicals.reaction.stoichiometry_MW_error(coefficients, MWs, reactants)[source]

This function calculates the molecular weight imbalance of a reaction given the coefficients and molecular weights of the involved components, and their statuses as reactants or product.

Parameters
coefficientslist[float]

Molar balanced stoichiometric coefficients; all numbers are positive, [-]

MWslist[float]

Molecular weights of all species in reaction ordered in the same way as the coefficients, [g/mol]

reactantslist[bool]

List of booleans indicating whether each chemical is a reactant (True) or a product (False), [-]

Returns
MW_errorfloat

The molecular weight error, [g/mol]

Notes

A very small value may be returned for a properly balanced equation because of floating-point error.

>>> stoichiometry_MW_error([4.0, 5.0, 4.0, 6.0], [17.03052, 31.9988, 30.0061, 18.01528], [True, True, False, False])
0.0
chemicals.reaction.standard_formation_reaction(atoms)[source]

This function calculates the standard reaction to reduce a chemical compound to its standard state elements. Any hydrogen in the compound is transformed to H2; oxygen to O2; carbon to graphite (single C), calcium to Ca, etc.

Parameters
atomsdict[(str, float)]

A dictionary of (element, element_count) pairs for the reacting compound, [-]

Returns
reactant_coefffloat

The coefficient of the reactant; for compounds like CO that do not divide evenly, this will be something other than 1 [-]

elemental_countslist[float]

Balanced coefficients of each of the products, [-]

product_atomsslist[dict[(str, float)]]

A list of dictionaries of the elements produced, and how many atoms of each element are in one unit of the element in its standard form. Each dictionary contains a single key:value, with the key being the element and the value being either 1 or 2 depending on the standard state [-]

Examples

Methane

>>> standard_formation_reaction({'C': 1, 'H': 4})
(1.0, [1.0, 2.0], [{'C': 1}, {'H': 2}])

Carbon monoxide

>>> standard_formation_reaction({'C': 1, 'O': 1})
(2.0, [2.0, 1.0], [{'C': 1}, {'O': 2}])

Methylamine

>>> standard_formation_reaction({'C': 1, 'H': 5, 'N': 1})
(2.0, [2.0, 5.0, 1.0], [{'C': 1}, {'H': 2}, {'N': 2}])