Critical Signal | Constants, Determination, Critical Phenomena |

Critical Point.

The bend representing the variation of book in addition to pressure level at constant temperature is called isotherm.

A gas tin hold out liquified yesteryear increasing pressure level in addition to decreasing temperature. At a temperature in addition to pressure, a gas changes to vapor. It is called the critical state of the gas. The indicate representing this solid soil inwards an isotherm is called critical point, e.g., F is a critical indicate inwards the isotherm CO2 at 31 °C.

Experimental Determination of Critical Constants.

Critical temperature in addition to pressure level tin hold out measured alongside Cagniard's apparatus. It is a U-shaped drinking glass subway scheme alongside a bulb at the lower end. The liquid is contained inwards the bulb in addition to the residuum of the apparatus is filled alongside mercury in addition to the upper in addition to of the bulb is sealed leaving a fiddling air inwards it. The temperature of the bulb is raised gradually. H5N1 indicate reaches when the liquid disappears in addition to a homogeneous mixture of vapors in addition to air is left inwards it. On cooling this mixture, a mist outset forms in addition to the liquid look quickly.

The hateful of the temperature of the disappearance in addition to reappearance of the liquid inwards the bulb is critical temperature. The pressure level read on the manometer is "critical pressure".

Determination of Critical Volume.

Amagat devised a method to decide the critical volume. It consists of mensuration the densities of liquid in addition to its vapors near the critical point. These ii densities are plotted against the temperature. When extended, these curves see at the critical temperature, because at this temperature the densities of liquid in addition to vapor croak equal. The hateful values of densities of liquid in addition to vapor are plotted in addition to nosotros gat CD which passed through C, the critical temperature. The intersection of CD in addition to ABC at C gives the critical density. From this, the critical book tin hold out calculated.

Critical Phenomena in addition to Critical State.

The essential atmospheric condition for the liquefaction of gas were discovered yesteryear T. Andrew. He made the conclusion alongside CO2 at diverse temperatures.

1. At 50 °C, CO2 obeys gas law, i.e., Boyle's Law.
2. At 31.1 °C, the Isotherm shows a interruption at F in addition to a decrease inwards book for a pocket-size modify pressure.
3. At 21 °C, the bend remains horizontal at YZ in addition to the gas changes to liquid at Y at the same pressure level although the book change.

At indicate F, at that topographic point exists an equilibrium betwixt the gas in addition to liquid, in addition to it exists inwards a vapor state. "The solid soil of a gas when it is introduce inwards vapor solid soil at definite temperature in addition to pressure level is called the critical state".

The indicate F is called a critical indicate in addition to the isotherm passing through it is called critical isotherm.