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Hess' Law

Given the bon...

Question

Given the bond energies $N \equiv N$ , $H - H$ and $N - H$ bonds are $945, 436$ and $391 k J m o l e^{- 1}$ respectively, the enthalpy of the following reaction $N_{2} (g) + 3 H_{2} (g) \to 2 N H_{3} (g)$ is

-93 kJ

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102 kJ

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90 kJ

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105 kJ

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Solution

The correct option is A
-93 kJ

$N \equiv N + 3 H - H \to 2 N | H | H - H$

$945 + 3 x 436$ $2 \times (3 \times 391) = 2346$

$E n e r g y a b s o r b e d     $ $E n e r g y r e l e a s e d     $

Net. Energy released = $2346 - 2253 = 93 k J$

i.e., $Δ H = - 93 k J$

Suggest Corrections

Similar questions

Q. The bond energies of

N \equiv N

H - H

and

N - H

bonds are

945,

436

and

391

KJ/mole respectively. The enthalpy of the reaction

N_{2} (g) + 3 H_{2} (g) \to 2 N H_{3} (g)

Given the bond energies $N \equiv N$ , $H - H$ and $N - H$ bonds are $945, 436$ and $391 k J m o l e^{- 1}$ respectively, the enthalpy of the following reaction $N_{2} (g) + 3 H_{2} (g) \to 2 N H_{3} (g)$ is

Q. Calculate the heat of formation of ammonia from the following data:

N_{2} (g) + 3 H_{2} (g) ⟶ 2 {N H}_{3} (g)

The bond energies of

N \equiv N, H - H

and

N - H

bonds are

226, 104

and

93

k c a l

respectively.

Q. Given are the bond enthalpies:

ϵ_{N \equiv N} = 945 {kJ mol}^{- 1}, ϵ_{H - H} = 436 {kJ mol}^{- 1}

and

ϵ_{(N - H)} = 391 {kJ mol}^{- 1}

. The enthalpy change of the reaction

N_{2} (g) + 3 H_{2} (g) \to 2 N H_{3} (g)

Q. The enthalpy of formation of ammonia when calculated from the following bond energy data is:

[B.E. of

N - H, H - H, N \equiv N

is 389 kJ

m o l^{- 1}

, 435 kJ

m o l^{- 1}

, 945.36 kJ

m o l^{- 1}

respectively]

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Given the bond energies N ≡ N, H − H and N − H bonds are 945,436 and 391 kJ mole−1 respectively, the enthalpy of the following reaction N2(g) + 3H2(g) → 2NH3(g) is

Given the bond energies $N \equiv N$ , $H - H$ and $N - H$ bonds are $945, 436$ and $391 k J m o l e^{- 1}$ respectively, the enthalpy of the following reaction $N_{2} (g) + 3 H_{2} (g) \to 2 N H_{3} (g)$ is