Ideal and Real Gases
Ideal gases obey conditions of the general gas laws under all states of pressure and temperature. Ideal gases are also named perfect gases. The attributes of ideal gases are as follows,
Gas Laws
Gas laws describe the ways in which volume, temperature, pressure, and other conditions correlate when matter is in a gaseous state. The very first observations about the physical properties of gases was made by Robert Boyle in 1662. Later discoveries were made by Charles, Gay-Lussac, Avogadro, and others. Eventually, these observations were combined to produce the ideal gas law.
Gaseous State
It is well known that matter exists in different forms in our surroundings. There are five known states of matter, such as solids, gases, liquids, plasma and Bose-Einstein condensate. The last two are known newly in the recent days. Thus, the detailed forms of matter studied are solids, gases and liquids. The best example of a substance that is present in different states is water. It is solid ice, gaseous vapor or steam and liquid water depending on the temperature and pressure conditions. This is due to the difference in the intermolecular forces and distances. The occurrence of three different phases is due to the difference in the two major forces, the force which tends to tightly hold molecules i.e., forces of attraction and the disruptive forces obtained from the thermal energy of molecules.
An open-ended manometer is used to measure gas pressure. What is the gas pressure if h=34.5 cm Hg? Atmospheric pressure is 760 mmHg
![This illustration depicts a U-tube manometer, which is used to measure the pressure of gas. The diagram shows the following components:
1. **Gas Supply**: On the left side, there is a container supplying gas to the U-tube manometer.
2. **U-tube Manometer**: The U-tube manometer consists of a transparent tube bent into a U-shape and partially filled with a liquid, typically mercury or water.
3. **Gas Inlet**: The gas from the supply enters the U-tube from one side, creating a difference in liquid levels.
4. **Open End**: The right side of the U-tube is open to the atmosphere, providing a reference pressure.
The diagram illustrates two significant points for measurements:
- **Patm**: The atmospheric pressure acting on the open end of the U-tube.
- **h**: The height difference between the liquid levels in the two arms of the U-tube, denoted by 'h'. This height difference is directly related to the pressure of the gas in the container.
The pressure in the gas container can be determined by the formula:
\[ P_{gas} = P_{atm} + \rho gh \]
where:
- \( P_{gas} \) is the pressure of the gas in the container
- \( P_{atm} \) is the atmospheric pressure
- \( \rho \) is the density of the liquid in the U-tube
- \( g \) is the acceleration due to gravity
- \( h \) is the height difference between the liquid levels in the U-tube
This principle allows for accurate measurement of the gas pressure relative to atmospheric pressure. The height difference 'h' is the key reading taken from the manometer to calculate the gas pressure.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F5c5734d7-71be-4626-8cb5-227ca6c7fb69%2Fc89ba1f2-723a-4de4-b4d6-0d7d09ba1786%2Fctifsbg_processed.jpeg&w=3840&q=75)
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