Question

Bond energies of few bonds are given below:

$Cl - Cl = 242.8kJmol^{- 1},H - Cl = 431.8kJmol^{- 1}$

$O - H = 464kJmol^{- 1},O = = O = 442kJmol^{- 1}$

Using the B.E. calculate $\Delta H$ for the following reaction,

$2Cl_{2} + 2H_{2}O \rightarrow 4HCl + O_{2}$

• A. $906kJmol^{- 1}$
• B. $172.4kJmol^{- 1}$
• C. $198.8kJmol^{- 1}$
• D. $442kJmol^{- 1}$

Answer 1

Answer: (B)

$172.4kJmol^{- 1}$

Answer 2

: $2Cl_{2} + 2H_{2}O \rightarrow 4HCl + O_{2}$

$\Delta H = B.E.$ of ($2 \times Cl - - Cl$) + $(2 \times 2 \times O - - H)$

$- (4 \times H - - Cl) + (O = = O)$

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