Why does NO2 undergo dimerisation at low temperature?

NO2 contains odd number of valence electrons. It behaves as an odd electron molecule and therefore undergoes dimerisation to form stable N2O4 molecule with even number of electrons.

Why does NO2 Dimerize to N2O4?

The presence of an unpaired electron on nitrogen makes it very reactive. It tries to dimerize and form a stable compound as N2O4 wit an even number of electrons.

What will happen to N2O4 if the temperature is increased?

As temperature is increased, the above reaction equilibrium shifts to the left, generating a higher concentration of NO2, resulting in the darkening of the reddish brown color inside the tube. Conversely, cooling the reaction shifts the equilibrium to the right, producing more N2O4 which is colorless.

Which component of the NO2 N2O4 equilibrium is favored by high temperatures which is favored by low temperatures?

At higher temperatures nitrogen dioxide is favored and at lower temperatures dinitrogen tetroxide is favored.

Why does NO2 change to solid on cooling?

Heat shifts the equilibrium in favor of NO2 and the tube becomes darker. Since the formation of N2O4 is an exothermic reaction, lowering the temperature shifts the equilibrium in favor of colorless N2O4. In a dry ice – acetone bath, the N2O4 will crystallizes as a white solid.

When temperature is lowered NO2 Dimerizes What is it accompanied by?

Thus, the dimerization of ${\text{N}}{{\text{O}}_{\text{2}}}$ as the temperature is lowered is accompanied by a decrease in paramagnetism. Thus, the correct option is option (D).

Why NO2 is Coloured but N2O4 is Colourless?

Its unpaired electron is responsible for its colour and its dimerization. At low pressures or at high temperatures, NO2 has a deep brown colour, but at low temperatures the colour almost completely disappears as NO2 dimerizes to form dinitrogen tetroxide, N2O4.

When a mixture of NO2 and N2O4 at equilibrium is cooled the intensity?

NO2 is brown and N2O4 is colorless. The intensity of the brown color decreases as the temperature decreases. Therefore, a decrease in temperature yields an increase in N2O4….Equilibrium of NO2/N2O4.

What will happen to the concentration of NO2 if the temperature is increased?

The NO2 is formed faster than it is used up, so it’s concentration increases. The N2O4 is used up faster than it is formed, so it’s concentration decreases. Since there are now more molecules of NO2 to run into each other, The rate of the reverse reaction will also speed up.

At what temperature does N2O4 decompose?

It is a useful reagent in chemical synthesis. It forms an equilibrium mixture with nitrogen dioxide. Its molar mass is 92.011 g/mol….Dinitrogen tetroxide.

What happens when NO2 is cooled?

If you cool NO2 gas down, its colour gets much paler. Eventually it changes from a brown gas to a colourless liquid.

Why is NO2 paramagnetic in gaseous state but the solid obtained on cooling is diamagnetic?

In gaseous state, NO2 exists as a monomer which has one unpaired electron but in solid state, it dimerises to so no unpaired electron left. Therefore, NO2 is paramagnetic in gaseous state but diamagnetic in solid state.