Question

In the detection of carbon, $C{O}_2$ formed after reaction with $CuO$ is tested by:

• A. $NaOH$
• B. $CaO$
• C. $Ca(OH{)}_2$
• D. $CuS{O}_4$

Answer 1

The correct option is C $Ca(OH{)}_2$

The given organic compound is mixed with dry copper oxide (CuO) and heated in a hard glass tube. The products of the reaction are passed over (white) anhydrous copper sulphate and then bubbled through lime water. If copper sulphate turns blue due to the formation of $CuS{O}_4.5H_{2}O$ (by water vapor) then the compound contains hydrogen.
If lime water i.e. $Ca(OH{)}_2$ is turned milky by $C{O}_2,$ then the compound contains carbon.
$C+2CuO\stackrel{\Delta }{\to }C{O}_2+2Cu$
$C{O}_2+\underset{\text{Limewater}}{Ca(OH{)}_2}\stackrel{\Delta }{⟶}CaC{O}_3\downarrow +H_{2}O$