Question

Using the data provided, calculate the multiple bond energy (kJ/mol) of a C $\equiv$ C bond of $C_2{H}_2.$ That energy is (take the bond energy fo a C - H bond as 350 kJ/mol)
$2C\left(s\right)+H_2\left(g\right)\to C_2{H}_2\left(g\right)△H=225kJ/mol$
$2C\left(s\right)\to 2C\left(g\right)△H=1410kJ/mol$
$H_2\left(g\right)\to 2H\left(g\right)△H=330kJ/mol$

• A. 1165
• B. 837
• C. 865
• D. 815

Answer 1

The correct option is D 815

$\underset{1410\underset{2C\left(g\right)}{\downarrow }}{2C\left(s\right)}+\underset{\underset{2H\left(g\right)}{\downarrow }330}{H_2\left(g\right)}\to C_2\underset{\uparrow 2{\epsilon }_{C-H}+{\epsilon }_{C\equiv C}}{H_2\left(g\right)}△H=225kJmol$
$\therefore △H=+1410+330-(350\times 2)-{\epsilon }_{C=C}=+225$
$\therefore {\epsilon }_{C=C}=1740-700-225=+815kJmol.$