Question
Explain bond enthalpy of diatomic molecules.
✓
Answer
In case of diatomic molecules, since there is only one bond, the bond enthalpy is equal to heat of atomisation. For example, heat of atomisation of $HCl _{( g )}$ is $431.9 kJ mol ^{-1}$.
$HCl _{( g )} \longrightarrow H _{( g )}+ Cl _{( g )} \quad \Delta_{ atm } H^0=431.9 kJ mol ^{-1}$
$\therefore$ Bond enthalpy of $HCl$,
$\begin{aligned}
\Delta_{\text {atm }} H^0 & =\frac{\Delta_{\text {atm }} H}{\text { Number of bonds broken }} \\
D_{ H - Cl } & =\frac{431.9}{1} \\
& =431.9 kJ mol ^{-1} \quad
\end{aligned}$
(Bond enthalpy is generally denoted by D).
$HCl _{( g )} \longrightarrow H _{( g )}+ Cl _{( g )} \quad \Delta_{ atm } H^0=431.9 kJ mol ^{-1}$
$\therefore$ Bond enthalpy of $HCl$,
$\begin{aligned}
\Delta_{\text {atm }} H^0 & =\frac{\Delta_{\text {atm }} H}{\text { Number of bonds broken }} \\
D_{ H - Cl } & =\frac{431.9}{1} \\
& =431.9 kJ mol ^{-1} \quad
\end{aligned}$
(Bond enthalpy is generally denoted by D).
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Why is KCl solution neutral to litmus?
How does ozone protect the people of the earth?
How much electricity in terms of Faraday is required to produce:
(a) $20 g$ of $Ca$ from molten $CaCl _2$
(b) $40 g$ of $Al$ from molten $Al _2 O _3$
(Given: Molar mass of Calcium and Aluminium are $40 g mol ^{-1}$ and $27 g mol ^{-1}$ respectively.)
→(a) $20 g$ of $Ca$ from molten $CaCl _2$
(b) $40 g$ of $Al$ from molten $Al _2 O _3$
(Given: Molar mass of Calcium and Aluminium are $40 g mol ^{-1}$ and $27 g mol ^{-1}$ respectively.)
A carbonyl compound $'A \ '$ having molecular formula $C _5 H _{10} O$ forms crystalline precipitate with sodium bisulphite and gives positive iodoform test but does not reduce Fehling solution. Write the structure of carbonyl compound.
→How is an aldehyde obtained from primary alcohol?
What are molecular crystals ?
What are the uses of hydrogen chloride (hydrochloric acid)?
Identify 'A' and 'B' and rewrite the reactions.
Explain the trend in the bond dissociation enthalpies of halogen molecules.