Mercury Barometer

  • It is the simplest device to measure atmospheric pressure at a location. It consists of a glass tube closed at one end immersed in a container filled with mercury.


  • Space in which there is no matter or in which the pressure is so low that any particles in the space do not affect any processes being carried on there. It is a condition well below normal atmospheric pressure and is measured in units of pressure (the pascal).


  • Mercury is a chemical element with the symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum.

Atmospheric Pressure

  • Atmospheric pressure, sometimes also called barometric pressure, is the pressure within the atmosphere of Earth. The standard atmosphere is a unit of pressure defined as 1,013.25 mbar, equivalent to 760 mm Hg, 29.9212 inches Hg, or 14.696 psi.

Kelvin Scale

  • The kelvin is the base unit of temperature in the International System of Units, having the unit symbol K. It is named after the Belfast-born, Glasgow University engineer and physicist William Thomson, 1st Baron Kelvin.
  • Zero on the Kelvin scale is the temperature where all motion of particles has ceased.
  • This absolute zero occurs at about -273.15 degree Celsius
  • A Kelvin has the same size as a degree Celsius


  • The mole is the SI unit for the amount of a substance and one of the seven fundamental SI units. It is defined as the amount of substance of a system that contains as many elementary entities as there are atoms in 0.012 kilograms of carbon-12.

Ideal Gases

  • An ideal gas has small point particles (relative to distant between them)
  • Only collisions (no interactions)
  • Elastic collisions (no energy lost)
  • Internal energy proportional to temperature

Boyle’s Law

  • Boyle’s law, most often referred to as the Boyle–Mariotte law, or Mariotte’s law, is an experimental gas law that describes how the pressure of a gas tends to increase as the volume of the container decreases.

Charles’s Law

  • Charles’s law is an experimental gas law that describes how gases tend to expand when heated. A modern statement of Charles’s law is: When the pressure on a sample of a dry gas is held constant, the Kelvin temperature and the volume will be in direct proportion.

Avogadro’s Law

  • Avogadro’s law is an experimental gas law relating the volume of a gas to the amount of substance of gas present. The law is a specific case of the ideal gas law. A modern statement is: Avogadro’s law states that “equal volumes of all gases, at the same temperature and pressure, have the same number of molecules.”

Ideal Gas Law

  • The ideal gas law, also called the general gas equation, is the equation of state of a hypothetical ideal gas. It is a good approximation of the behavior of many gases under many conditions, although it has several limitations.

Heat Capacity

  • It is the amount of heat required to change its temperature by one degree, and has units of energy per degree.
  • Heat capacity C is how much energy is required per unit temperature and has units (C) = J/K
  • Specific heat is how much energy is required per unit temperature for a given amount of mass.

Van der Waals’ Equation

  • The van der Waals equation is an equation of state that generalizes the ideal gas law based on plausible reasons that real gases do not act ideally.

Partial Pressure

  • In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas if it alone occupied the entire volume of the original mixture at the same temperature. The total pressure of an ideal gas mixture is the sum of the partial pressures of the gases in the mixture.