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Chemistry formula for class 12 chapter- surface chemistry

Chemistry Formulas

  • Adsorption: The existence of a substance at a surface in different concentration than in the adjoining bulk is called adsorption.
  1. O2, H2, CO, Cl2, NH3, or SO2, get adorbed on the surface of charcoal.
  2. Undesirable colours of organic compounds can be removed by animal charcoal.
  3. Colour from sugar can be removed by activated charcoal.
  4. Silica gel adsorbs water molecules so as to protect electronic components.
  • Adorbate: The substance which is being adsorbed on the surface of another substance is called adsorbate.
  • Adsorbent: The substance present in bulk, on the surface of which adsorption is taking place is called adsorbent. Solids in finely divided state have large surface area and therefore, charcoal, silica gel, alumina gel, clay, colloids, metals etc. are good adorbents.
  • Desorption: The process of removing an adsorbed substance from a surface on which it is adsorbed is called desorption. Silica gel 9. removes water, animal charcoal removes colour from surface of organic compounds.
  • Sorption: When adsorption and absorption take place simultaneously, it is called sorption, e.g., dying of cotton fabrics. The dye is adsorbed on the surface of cotton fibre but after it is dyed, the fibre has dye uniform throughout.
  • Enthalpy or heat of adsorption: Adsorption generally occurs with release in energy, i.e., it is exothermic in nature. The enthalpy for the adsorption of one mole of an adsorbate on the surface of adsorbent is called enthalpy or heat of adsorption.
  • Characteristics of physisorption :
  1. It is reversible.
  2. It has weak van der Waals' forces of attraction with adsorbent.
  3. It has low heat of adsorption.
  4. It takes place at low temperature and decreases with increase in temperature.
  5. It increases with increase in pressure.
  6. It forms multimolecular layer
  • Characteristics of chemical adsorption :
  • It is irreversible.
  • It has strong forces of attraction with adsorbent like chemical bonds.
  • It forms unimolecular layer.
  • It has high heat of adsorption.
  • It takes place at moderate temperature.
  • It first increases and them becomes. independent of pressure.
  • It increases with increase in temperature and then decreases.
  • Homogeneous Catalysis: When the catalyst mixes homogeneously with the reactant (s) and forms a single phase, the catalyst is said to be homogeneous and this kine of catalysis is known as homogeneous catalysis e.g.,Catalytic oxidation of SO2, to SO3, in presence of NO is an example of homogeneous catalysis.

homogenous catalyst

  • Heterogeneous catalysis: When the catalyst forms a separate phase (usually a solid phase), it is said to be heterogeneous and the catalysis is heterogeneous catalysis. Example of heterogeneous catalysis is manufacture of H2SO4 in contact process using V2O5 as catalyst. Usually in a heterogeneous catalysis the reactant are gases, and reaction starts from the surface of the solid catalyst. This is the reason why heterogeneous catalysis is also called ‘surface catalysis’.

heterogenous

Chemistry formula sheet for chapter-surface chemistry is prepared by expert of Physics Wallah and consist of all-important formula use in surface chemistry chapter. Find NCERT solutions prepared by experts of Physics Wallah. Students can also access the class 12 chemistry notes from here. If any students need to take the online test to check their concepts or undertstanding then they can visit Quiz for Surface Chemistry.

Download free pdf sheet which consist of formulas and important points of Surface Chemistry

Chemistry formula for class 12 chapter- surface chemistry

Chemistry formula for class 12 chapter- surface chemistry

Chemistry formula for class 12 chapter- surface chemistry

Chemistry formula for class 12 chapter- surface chemistry

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