Question

The enthalpy of the reaction forming $PbO$ according to the following equation is $438kJ$. What heat energy (kJ) is released in formation of $22.3gPbO\left(s\right)$?
(At. wt. $Pb=207,O=16.0)$
$2Pb\left(s\right)+O_2\left(g\right)\to 2PbO\left(s\right)$.

• A. $21.9$
• B. $28.7$
• C. $46.14$
• D. $34.2$

Answer 1

Answer: (A)

$21.9$

The given reaction is forming the $2$ mole of $PbO$, it means

Wt Of $PbO=2\times 223=446gm$

$\because$ formation of $2$ mol of $PbO$ relaesed energy $=438KJ$

$\therefore$ formation of $1$ mol of $PbO$ will release energy $=\frac{438}{2}$

$\therefore$ formation of $.1$ mol of $PbO$ will release energy$=438\times .12=21.9KJ$