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Heat of Formation

Using the bon...

Question

Using the bond enthalpy data given below, calculate the enthalpy of formation of acetone (g)
Bond energy $C - H = 413.4 k J {m o l}^{- 1}$ ;
Bond energy $C - C = 347.0 k J {m o l}^{- 1}$ ;
Bond energy $C = O = 728.0 k J {m o l}^{- 1}$ ;
Bond energy $O = O = 495.0 k J {m o l}^{- 1}$ ;
Bond energy $H - H = 435.8 k J {m o l}^{- 1}$ ;
$Δ H_{s u b} C (s) = 718.4 k J {m o l}^{- 1}$

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Solution

$3 C (g) + 6 H (g) + O (g) \to {C H}_{3} C O {C H}_{3} (g)$
In acetone, six $C - H$ bonds, one $C = O$ bond and two $C - C$ bonds are present. Energy released in the formation of these bonds is
$= - 6 \times 413.4 - 728.0 - 2 \times 3470 = - 3902.4 k J {m o l}^{- 1}$
The equation of the enthalpy of formation of acetone is
$3 C_{g r a p h i t e} + 3 H_{2} (g) + \frac{1}{2} O_{2} (g) \to {C H}_{3} C O {C H}_{3} (g); Δ H = ?$
This equation can be obtained from the following equations by adding:
$3 C (s) + 6 H (g) + O (g) \to {C H}_{3} C O {C H}_{3} (g); Δ H = - 3904 k J {m o l}^{- 1}$
$3 C (s) \to 3 C (g); Δ H = 2155.2 k J {m o l}^{- 1}$
$3 H_{2} \to 6 H (g); Δ H = 1307.4 k J {m o l}^{- 1}$
and $\frac{1}{2} O_{2} (g) \to O (g); Δ H = 247.5 k J {m o l}^{- 1}$
---------------------------------------------------------------------------------------------
$3 C (s) + 3 H_{2} (g) + \frac{1}{2} O_{2} (g) \to {C H}_{3} C O {C H}_{3} (g); Δ H = - 192.3 k J {m o l}^{- 1}$

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Similar questions

H | C | H = H | C | H + H - H \to H - H | C | H - H | C | H - H

H - H

431.37 k J m o l^{- 1}

C = C

606.10 k J m o l^{- 1}

C - C

336.49 k J m o l^{- 1}

C - H

410.50 k J m o l^{- 1}

H - - H

O - - O

O - - H

433 k J m o l^{- 1}

492 k J m o l^{- 1}

464 k J m o l^{- 1}

(N - N)

= 398 k J {m o l}^{- 1}

(H - H)

= 435 k J {m o l}^{- 1}

(N \equiv N)

= 945.36 k J {m o l}^{- 1}

(k J m o l^{- 1})

C \equiv C

C_{2} H_{2} .

C_{2} H_{2} = 225 k J m o l^{- 1} .

C - H

350 k J m o l^{- 1}

2 C (s) \to 2 C (g) △ H = 1410 k J m o l^{- 1}

H_{2} (g) \to 2 H (g) △ H = 330 k J m o l^{- 1}

C - H = 415; C - C = 350; (C = O) = 730

(O = O) = 495.0; H - H = 435;

Δ_{s u b} H

= 720

^{- 1}

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