States Of Matter Class 11 Notes - Chapter 5

The intermolecular forces run between the particles of matter. There exists a pure electrostatic force between two ions which are oppositely charged. The intermolecular forces are different from these pure electrostatic forces. Determining the state of matter is done by the competition between intermolecular interactions and thermal energy. Various properties of matter in bulk such as a change in state, characteristics of liquids and solids, gases behavior depends on two factors:

  • The interaction type between them
  • The energy of constituent particles

The change of state does not affect the chemical properties of a substance, but the change in physical state affects the reactivity.

Boyle’s Law

Charles’s Law states that the volume of a given mass of gas is directly proportional to the absolute temperature at constant pressure. It is expressed as PV = k where P is pressure, V is volume and k is constant. This law is also referred to as the Boyle-Mariotte law or Mariotte’s law.

Charles’ Law

Charles’s Law states that the volume of a given mass of gas is inversely proportional to the absolute pressure at a constant temperature. It is expressed as V/T = k where V is the volume of gas, T is the temperature of the gas, and k is constant. The temperature is measured in Kelvin scale. This law is also termed as the law of volumes.

Few Important Questions

  1. Given: Quantity of gas = 4.0 mol occupies 5 dm3, Pressure = 3.32 bar, R = 0.083 bar dm3 K-1 mol-1.
  2. Calculate the molar mass of phosphorous with the following details:

The quantity phosphorus vapor is 34.05 mL and weight is 0.0625 g. At 0.1 bar pressure and 546 °C temperature.

  1. What is the physical importance of van der Waals parameters? Explain.

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Practise This Question

You have but one molecule of Hydrogen (H2), meandering about in the vast emptiness of a 1cm3 closed box, at a speed of 500 m/s, bouncing off from one wall to the next. What are the rms speed and the temperature inside the box?