1. Tardigrade
  2. Question
  3. Chemistry
  4. Silanes are silicon hydrides of general formula SinH2 n + 2 and have several applications. From the data given below, the bond dissociation enthalpy of Si-Si bond (in kJmol- 1 ) is Given: Δ H of the reaction 2Si(s)+3H2(g) arrow Si2H6(g) is 80.3kJmol- 1 Bond dissociation enthalpy for H-H=436kJmol- 1 Bond dissociation enthalpy for Si-H=304kJmol- 1 (Δ )fH [S i (g)]=405 kJmol- 1 (Note: Report your answer after rounding up to the nearest integer value.)

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. Silanes are silicon hydrides of general formula $Si_{n}H_{2 n + 2}$ and have several applications. From the data given below, the bond dissociation enthalpy of $Si-Si$ bond (in $kJmol^{- 1}$ ) is
Given:
$\Delta H$ of the reaction $2Si\left(s\right)+3H_{2}\left(g\right) \rightarrow \, Si_{2}H_{6}\left(g\right)$ is $80.3kJmol^{- 1}$
Bond dissociation enthalpy for $H-H=436kJmol^{- 1}$
Bond dissociation enthalpy for $Si-H=304kJmol^{- 1}$
$\left(\Delta \right)_{f}H \, \left[S i \left(g\right)\right]=405 \, kJmol^{- 1}$
(Note: Report your answer after rounding up to the nearest integer value.)

NTA AbhyasNTA Abhyas 2022

Solution:

$2Si\left(s\right)+3H_{2}\left(g\right) \rightarrow \, \left(Si\right)_{2}H_{6}\left(g\right)\Delta H_{1}=80.3\left(kJmol\right)^{- 1}$
$H_{2}\left(g\right) \rightarrow 2H\left(g\right)\Delta H_{2}=436\left(kJmol\right)^{- 1}$
$\Delta H_{reaction}=\underset{}{\displaystyle \sum }BEofreactants-\underset{}{\displaystyle \sum }BEofproducts$
$\Delta H_{reaction}=2\times \Delta H_{sublimation of Si \left(s\right)}+3\times \left(BE\right)_{H - H}-6\times \left(BE\right)_{Si - H}+\left(BE\right)_{si - si}$
$80.3=2\times 405+3\times 436-\left[\left(S i - S i\right) + 6 \left(304\right)\right]$
(Si - Si) Bond energy $=214 \, kJmol^{- 1}$