Blog / Gas Phase Gc Phy Ideal Gas

### Gas Phase (GC, PHY): Ideal gas

Written by Chau Pham on Feb 26, 2020

Ideal gas exhibits no attractive interactions between particles. The Ideal Gas Equation is given by:

PV=nRT

The four variables represent four different properties of a gas:

• Pressure (P), often measured in Pascal (Pa). If pressure is given in atmosphere (atm) or millimeters mercury/torr (mmHg, torr), it would be easier to solve the problem changing the pressure into Pascal.
• Volume (V), given in liters
• Number of moles of gas (n)
• Temperature of the gas (T) measured in degrees Kelvin (K)
• R = 8.3145 J·mol-1·K-1, is the ideal gas constant

At high temperatures and low pressures, gases behave close to ideally. Pressure and volume are directly proportional to temperature of ideal gas. The kinetic energy of gas particles is dependent upon temperature only.

Boyle’s Law an inverse relationship exists between pressure and volume. Boyle’s Law holds true only if the number of molecules (n) and the temperature (T) are both constant. The relationship for Boyle’s Law can be expressed as follows: P1V1 = P2V2, where P1 and V1 are the initial pressure and volume values, and P2 and V2 are the values of the pressure and volume of the gas after change.

Charles’ Law: at constant pressure (P), the volume of a given mass of an ideal gas increases or decreases by the same factor as its temperature on the absolute temperature scale (i.e. gas expands as temperature increases). V1/T1=V2/T2

Avogadro’s Law states that The number of molecules or atoms in a specific volume of ideal gas is independent of size or the gas’ molar mass. V/n = k, where V is the volume of the gas, n is the number of moles of the gas, and k is a proportionality constant.

KEY TAKEAWAY

Key Points:

• An ideal gas exhibits no attractive forces between particles.
• The Ideal Gas Equation: PV=nRT
• Boyle’s Law: P1V1 = P2V2
• Charles Law: V1/T1=V2/T2
• Avogadro’s Law: V/n = k

## Key terms:

• Ideal gas: a gas whose particles exhibit no attractive interactions.
• Kinetic energy: the energy possessed by an object because of its motion.

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