Question

State two relevant observations for each of the following:
Lead nitrate crystals are heated in a hard glass tube.

Answer 1

Hint: Lead $\left( {Pb} \right)$ belongs to Group 14 of p- block elements. Its atomic number is 82 and its electronic configuration is $\left[ {Xe} \right]4{f^{14}}5{d^{10}}6{s^2}{p^2}$ . A decomposition reaction is a reaction in which a single compound or a single reactant breaks down on heating into two or simpler substances. The general form of a decomposition reaction is ${{AB}} \to {{A + B}}$

Complete step by step answer:
Now we will tell you about the relevant observations:
Lead nitrate on heating gives more than one product, hence a decomposition reaction. Lead nitrate crystals on heating in a hard glass tube decompose to give lead oxide $\left( {PbO} \right)$ , nitrogen dioxide $\left( {N{O_2}} \right)$ , and oxygen $\left( {{O_2}} \right)$ . The above decomposition reaction is :
 $2Pb{\left( {N{O_3}} \right)_2}\xrightarrow{{heat}}2PbO + 4N{O_2}\left( g \right) + {O_2}\left( g \right)$
During heating lead, nitrate decreases which means that a crackling sound is produced (noise produced when chemical compounds are heated) and we can see a yellow color residue of lead oxide is formed which fuses with the glass.
A reddish-brown gas of nitrogen dioxide is released which has an irritating smell. The gas turns moist blue litmus paper into the red. Hence, it is an acidic gas.
Also, colorless gas oxygen is liberated during the reaction.
So these are the two relevant observations we can observe when lead nitrate is heated in a hard glass tube.

Note:
The input of energy in the form of heat, light, or electricity is required by most of the decomposition reactions. The compounds composed of just two elements are termed as binary compounds. The simplest example of a decomposition reaction is when a binary compound decomposes into its elements. For example- Mercury (II) oxide, a red solid, decomposes when heated to produce mercury and oxygen gas. The reaction involved is ${{2HgO}}\left( {{s}} \right) \to {{2Hg}}\left( {{l}} \right){{ + }}{{{O}}_{{2}}}\left( {{g}} \right)$