Qualitative Analysis - Result Question 48
51. $A _1$ and $A _2$ are two ores of metal $M . A _1$ on calcination gives black precipitate, $CO _2$ and water.
Identify $A _1$ and $A _2$.
(2004)
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Solution:
$A _1=Cu(OH) _2 \cdot CuCO _3$ and $A _2=Cu _2 S$
$A _1 \xrightarrow{\text { Calcination }} \underset{\text { Black } }{2 CuO}+CO _2+H _2 O $
$A _1 \xrightarrow{\text { Dil. } HCl} CuCl _2 +CO _2+H _2 O $
$2 CuCl _2+4 KI \longrightarrow 2 CuI+I _2+4 KCl $
$2 Cu _2 S\left(A _2\right)+3 O _2 \longrightarrow 2 Cu _2 O+2 SO _2 $
$Cu _2 S+2 Cu _2 O \stackrel{\Delta}{\longrightarrow} 6 Cu+SO _2$
BETA
