# Sulfur Oxygen Equilibrium

This example shows equilibrium calculations for sulfur/oxygen mixtures.


```python
import gaspype as gp
import numpy as np
import matplotlib.pyplot as plt
```

List possible sulfur/oxygen species:


```python
gp.species(element_names = 'S, O')
```




    ['O',
     'O2',
     'O3',
     'S',
     'S2',
     'S2O',
     'S3',
     'S4',
     'S5',
     'S6',
     'S7',
     'S8',
     'SO',
     'SO2',
     'SO3']



Or more specific by using regular expressions:


```python
gp.species('S?[2-3]?O?[2-5]?', use_regex=True)
```




    ['O', 'O2', 'O3', 'S', 'S2', 'S2O', 'S3', 'S4', 'S5', 'SO', 'SO2', 'SO3']



Calculation of the molar equilibrium fractions for sulfur and oxygen depending on the oxygen to sulfur ratio:


```python
fs = gp.fluid_system(['S2', 'S2O', 'SO2', 'SO3', 'O2'])

oxygen_ratio = np.linspace(0.5, 3, num=128)
el = gp.elements({'S': 1}, fs) + oxygen_ratio * gp.elements({'O': 1}, fs)

composition = gp.equilibrium(el, 800+273.15, 1e4)

fig, ax = plt.subplots()
ax.set_xlabel("Oxygen to sulfur ratio")
ax.set_ylabel("Molar fraction")
ax.plot(oxygen_ratio, composition.get_x(), '-')
ax.legend(composition.species)
```




    <matplotlib.legend.Legend at 0x7effee4aaa50>




    
![png](sulfur_oxygen_equalibrium_files/sulfur_oxygen_equalibrium_7_1.png)
    


Calculation of the molar equilibrium fractions for sulfur and oxygen depending on temperature in °C:


```python
fs = gp.fluid_system(['S2', 'S2O', 'SO2', 'SO3', 'O2'])

el = gp.elements({'S': 1, 'O':2.5}, fs)

t_range = np.linspace(500, 1300, num=32)
composition = gp.equilibrium(el, t_range+273.15, 1e4)

fig, ax = plt.subplots()
ax.set_xlabel("Temperature / °C")
ax.set_ylabel("Molar fraction")
ax.plot(t_range, composition.get_x(), '-')
ax.legend(composition.species)
```




    <matplotlib.legend.Legend at 0x7effee383c50>




    
![png](sulfur_oxygen_equalibrium_files/sulfur_oxygen_equalibrium_9_1.png)