MyQuestionIcon

1

You visited us 1 times! Enjoying our articles? Unlock Full Access!

Enthalpy of Combustion

Calculate the...

Question

Calculate the enthalpy of formation of acetic acid ( $C H_{3} C O O H$ ) if its enthalpy of combustion is $- 867 k J m o l^{- 1}$ .The enthalpies of formation of $C O_{2} (g)$ and $H_{2} O (l)$ are -393.5 and $- 285.9 k J m o l^{- 1}$ respectively.

Open in App

Solution

Solution:-
Let enthalpy of formation of acetic acid be $x k J / m o l$ .
Combustion of ethane-
$C H_{3} C O O H + 3 {O_{2}}_{(g)} ⟶ 2 {C O_{2}}_{(g)} + 2 {H_{2} O}_{(l)} Δ H = - 867 k J / m o l$
$Δ H^{0} = {\sum Δ {H^{0}}_{f}}_{(p r o d u c t)} - {\sum Δ {H^{0}}_{f}}_{(r e a c t a n t)}$
$∴ - 867 = (2 \times (- 393.5) + 2 \times (- 285.9)) - (x + 0)$
$\Rightarrow x = - 1358.8 + 867 = - 491 k J / m o l$
Hence the enthalpy of formation of acetic acid will be $- 491 k c a l / m o l$ .

Suggest Corrections

thumbs-up

1

Similar questions

Q. The enthalpies of formation of

C O_{2 (g)}, H_{2} O_{(l)}

C_{2} H_{4 (g)}

are respectively

- 393.5, - 286

+ 52.3 k J m o l^{- 1}

. The enthalpy change for the combustion of

C_{2} H_{4 (g)}

Q. The enthalpy of the formation of

C O_{2}

H_{2} O

- 395 k J

- 285 k J

respectively and the enthalpy of combustion of acetic acid is

869 k J

. The enthalpy of formation of acetic acid is:

Q. The standard enthalpy of formation of octane

(C_{8} H_{18})

- 250 kJ/mol

. Calculate the enthalpy of combustion of

C_{8} H_{18}

. Given that enthalpy of formation of

C O_{2} (g)

H_{2} O (l)

- 394 kJ/mol

- 286 kJ/mol

Q. From the following data, calculate the enthalpy change for the combustion of cyclopropane at 298 K. The enthalpy of formation of

C O_{2} (g), H_{2} O (l)

and propane (g) are -393.5, -285.8 & 20.42 kJ/mol respectively. The enthalpy of isomerisation of cyclopropane to propene is -33.0 kJ/mol.

300 K

the standard enthalpies of formation of

C_{6} H_{5} C O O H (s), {C O}_{2} (g), H_{2} O (l)

- 408, - 398

- 286 k J {m o l}^{- 1}

respectively. Calculate the heat of combustion of benzoic acid at constant volume:

View More

Join BYJU'S Learning Program

similar_icon

Related Videos

lock

Thermochemistry

CHEMISTRY

Watch in App

explore_more_icon

Explore more

Enthalpy of Combustion

Standard XII Chemistry

Join BYJU'S Learning Program

CrossIcon