Question

Methane is quite stable, whereas silane is unstable because

• A. $C— \, C$ bond energy is much greater than $Si—Si$ bond energy
• B. $Si—H$ bond energy is much lower than $C—H$ bond energy
• C. $Si$ has vacant $p-$ orbitals which are more susceptible for nucleophilic attack
• D. All of above reasons

Answer 1

Answer: (B)

$Si—H$ bond energy is $393 \, k J / m o l$
Whereas, $C—H$ bond energy is $435 \, k J / m o l$
$D_{C — C} \, \sim eq \, 340 \, k J / m o l \, \& \, D_{S i — S i}\sim eq368 \, k J / m o l$
$C—C$ and $Si—Si$ bond energies are comparable, while $\text{Si} - \text{H}$ bond energy is lower than $\text{C} - \text{H}$ bond energy, so methane is quite stable, whereas silane is unstable.