Question

What is the colour of lead oxide when it is hot and when it is cold?

Answer 1

Hint: Lead is the last member of the carbon family therefore many of its properties resemble carbon but some may vary like the nature of oxides, reactivity etc. lead form colored compounds because they have metallic properties to absorb the radiation and re-emit it into visible range.

Complete Step By Step Answer:
Lead reacts with oxygen to form its monoxide which is represented as $ \left( {PbO} \right) $ . Lead oxide is amphoteric in nature because it reacts with both acid as well as base.
Lead oxide is colored oxide which exists as a red colour before application of heat over it. a naturally stable form of lead oxide occurred as dark red colour with its oxidation number $ \left( { + 4} \right) $ . When we apply heat over the lead oxide it changes its colour to yellow. This newly generated yellow colored oxide of lead is naturally unstable and as the temperature falls down it again changes into its stable form which is red in colour. Yellow colored oxide of lead is also known as meta-stable oxide.
When lead oxide is heated it absorbs the energy and emits the wavelength in the visible region which is of $ 580 nm $ which is also equivalent to the wavelength of yellow colour in electromagnetic spectrum.
 $ Pb{O_{\left( {red} \right)}} + 1.6kJ/mol \to Pb{O_{\left( {yellow} \right)}} $
Lead oxide which exists as a tetragonal structure possesses red colour while the orthorhombic structure of lead oxide is yellow in colour.

Note:
Lead also exists as dioxide by reacting with oxygen and forms two basic polymers namely alpha and beta polymer. Alpha polymers that occur naturally are known as scrutinyite while beta form is known as plattnerite.