Elements of Groups 16, 17 and 18 — Chemistry STD 12 Science — Question
Maharashtra BoardEnglish MediumSTD 12 ScienceChemistryElements of Groups 16, 17 and 183 Marks
Question
Explain the laboratory methods for the preparation of dioxygen.
✓
Answer
(i) By heating chlorates, nitrates and permanganates. Potassium chlorate in the presence of manganese dioxide on heating decomposes to form potassium chloride and oxygen. $2 KClO _3 \xrightarrow[ MnO _2]{\Delta} 2 KCl +3 O _{2( g )}$ (ii) By the thermal decomposition of metal oxides. $\begin{aligned} & 2 Ag _2 O _{( s )} \xrightarrow{\text { heat }} 4 Ag + O _{2( g )} \\ & 2 HgO _{( s )} \xrightarrow{\text { heat }} 2 Hg + O _{2( g )} \\ & 2 PbO _{2( s )} \xrightarrow{\text { heat }} 2 PbO _{( s )}+ O _{2( g )} \end{aligned}$ (iii) By the thermal decomposition of hydrogen peroxide : The thermal decomposition of hydrogen peroxide in the presence of finely divided metal and manganese dioxide used as catalyst gives oxygen. \92 H _2 O _{2 \text { (aq) }} \xrightarrow[ MnO _2]{\text { heat }} 2 H _2 O _{( l )}+ O _{2( g )}$
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.