Chemistry: States of Matter: Intermolecular Interaction and its Types and General Behavior of gases-the gas laws

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The Three States of Matter

Image of Gaseous and Liquid States

Image of Gaseous and Liquid States

  • Solid, Liquid and Gas are the three distinct physical forms of matter.

  • All the three states of matter are made up of small tiny particles with a particular mass and can occupy space.

  • Solid consists of tightly packed particles; the particles are not free to move around.

  • Liquid is the state of matter with a definite volume but no fixed shape. In liquid the molecules are free to move around and are loosely packed as compared to the solids.

  • Gas as a state of matter is defined as the one with no fixed shape and no fixed volume. The molecules in gas are very loosely packed and are free to move around.

Intermolecular Interaction and Its Types

Image of Intermolecular Interaction and its Types

Image of Intermolecular Interaction and Its Types

  • Intermolecular interactions occur between all types of molecules or ions in all states of matter.

  • Liquids have less intermolecular forces then solid but higher than gases.

  • There are three major types of intermolecular forces: London dispersion force, dipole-dipole interaction, and ion-dipole interaction.

General Behavior of Gases-The Gas Laws

  • The gas laws consist of three primary laws: Charles’ Law, Boyle’s Law and Avogadro’s Law.

  • According to Boyle’s law, if the temperature of a gas is held constant, increasing the volume of the gas decreases its pressure.

  • Avogadro’s law is a gas law that relates to the volume of a gas to the amount of substance of gas present. It is an experimental gas law.

Ideal Gas Equation

Image of Ideal Gas Equation

Image of Ideal Gas Equation

  • If we combine the Boyle’s law, Charle’s law and Avogadro’s law, we get an equation and V/T=k, PV/T=constant, the ideal gas equation obtained is where P= pressure of the gas; V=volume of the gas; n= Number of Moles; T=Absolute temperature; R=Ideal Gas constant also known as Boltzmann Constant = 0.082057 L atm

  • It is possible to study any gas using equation under the assumptions of Standard Temperature and Pressure i.e. STP.

Dalton’S Law of Partial Pressure

Image of Dalton's law of partial pressure

Image of Dalton's Law of Partial Pressure

  • The Sum of the partial pressures of the component gases is equal to the total pressure of a mixture of gases. Pressure Total = Pressure Gas 1 + Pressure Gas 2 + Pressure Gas 3 + ...

  • The total pressure of a mixture of gases can be defined as the sum of the pressures of each individual gas:

  • The partial pressure of an individual gas is equal to the total pressure multiplied by the mole fraction of that gas.

  • Dalton’s law allows us to calculate the total pressure in a system from each gas individual contribution.

Kinetic Molecular Theory of Gases

Image of Kinetic molecular theory of gases

Image of Kinetic Molecular Theory of Gases

  • The average kinetic energy of a collection of gas particles is directly proportional to absolute temperature only.

  • This theory also states that gas particles are in constant motion and exhibit perfectly elastic collisions.

Kinetic Energy and URms

  • The energy that an object or body possesses by virtue of its motion is called the kinetic energy. For e.g. person walking, a thrown flying disc etc.

  • The root means square velocity (RMS velocity) is a way to find a single velocity value for the particles. The average velocity of gas particles is found using the root mean square velocity formula.

Graham’S Law of Diffusion

Image of Graham's Law of Diffusion

Image of Graham's Law of Diffusion

  • It states that the rate of diffusion or of effusion of a gas is inversely proportional to the square root of its molecular weight.

  • = =

Real Gases – Deviation from Ideal Gas Behavior

Image of Real gases deviation from ideal gas behavior

Image of Real Gases Deviation from Ideal Gas Behavior

  • The volume occupied by gas molecules is negligibly small as compared to the volume occupied by the gas.

  • The forces of attraction between gas molecules are negligible.

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