# Objective:

**In this experiment, we are aiming to determine the Joule Thomson coefficient ( ) of CO2 and N2 gases.**

# Equipments:

**Joule-Thomson apparatus, digital temperature meter, two temperature probes. Two vacuum rubbers tubing, reduce valves for CO2 and N2 two steel cylinders for CO2 and N2 gases, 10 liters capacity each.**

# Theory:

**In real gases, the internal energy U is composed of a thermo kinetic content : the potential of the intermolecular forces of attraction. This is negative and tends towards zero as the molecular distance increases. In real gases, the internal energy is therefore a function of the volume while the internal energy for ideal gas is a function of temperature only and hence:**

**During adiabatic expansion ( and during which also no external work done, the overall internal energy remains unchanged, with the result that potential energy increases at the expanses of the thermo-kinetic content and the gas cools.**

**H1=U1+P1V1=U2+P2+V2=H2**

**In this equation, PV is the work performed by an imaginary piston during the flow of a small amount of gas by a change in piston 1 to 2 or piston 3 to 4 (Fig-2).**

**In real gases, the displacement work PV does not equal to the displacement work equal the displacement work P V: in this case: P1V1 P2V2**

# Procedure:

**First of all , the reducing valves of the steel cylinder area screwed and the main valves tightness area checked too. The steel cylinders are put on a secure location. The vacuum between the reducing valve and the Joule-Thomson apparatus is attached with hose tube clips. A temperature probe on the un-pressurized side to inlet 2 of the temperature measurements apparatus**.

# Results:

P | N2 | CO2 |

1 | 0 | 0.52 |

0.9 | -0.005 | 0.49 |

0.8 | -0.015 | 0.46 |

0.7 | -0.013 | 0.42 |

0.6 | -0.015 | 0.39 |

0.5 | -0.017 | 0.31 |

0.4 | -0.024 | 0.24 |

0.3 | -0.025 | 0.15 |

0.2 | -0.026 | 0.08 |

0.1 | -0.028 | 0.01 |

0 | -0.032 | 0 |

# Graph:

P (bar) | |

0 | 0 |

0.9 | 0.09 |

0.8 | 0.13 |

0.7 | 0.16 |

0.6 | 0.22 |

0.5 | 0.24 |

0.4 | 0.27 |

0.3 | 0.3 |

0.2 | 0.33 |

0.1 | 0.4 |

0 | 0.43 |

# Calculations:

**From the slope equation in the graph we get:**

**Y= 7 * 106 -0.0614 for CO2 y= 7 * 10-7 X-0.2364 for N2**

**Y=mx +c y=mx+c**

**Slope = 7 * 10-6- Slope = 7 * 10-7**

**Therefore,**

**ÃÂµJT = 7 * 10-7 K\Pa for N2**

**ÃÂµJT = 7 * 10-6- K\Pa for CO2**

**Van Der Waals**

**-For Co2**

**= 9.43 * 10-4 K/Pa**

**-For N2**

**=-7.4 * 10-3 K/Pa**

**The literature value for CO2: is ÃÂµCO2= 1.16 * 10 -5 K/Pa**

**The literature valve for N2 : is ÃÂµN2=**

**Co2:**

**Experimental value VS. Literature valve**

**7*10 -6 K/Pa Vs 1.16 * 105 K/Pa**

**=**

**= 39.6 %**

**N2:**

**Experimental value Vs Literature value**

**7* 10-7 K/Pa Vs 1.16 * 10-5 K/Pa**

**= * 100**

**= 72 %**

# Conclusion:-

**From this experiment we can determine the Joule Thomson coefficient ( ÃÂµ) of CO2 and N2 gases. Also The experimenting room and the experimental apparatus**

**Must be in a thermal equilibrium at the start of the measurement.**

**The experimental apparatus should be kept out of direct**

**Sunlight and other sources of heating or cooling.**