MyQuestionIcon

1

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

Internal Energy

The standard ...

Question

The standard enthalpies of formation at 300 K for $C C l_{4} (l), H_{2} O (g), C O_{2} (g) a n d H C l (g) a r e - 107, - 242, - 394 a n d - 93 k J m o l^{- 1},$ respectively. The value of $△ U_{300}^{o}$ for the reaction:

$C C l_{4} (l) + 2 H_{2} O (g) \to C O_{2} (g) + 4 H C l (g)$ is
$- x k J m o l^{- 1}$ . Find the value of $x$
(Take $R = 8.314 J K^{- 1} m o l^{- 1}$ )

Open in App

Solution

For the reaction $C C l_{4} (l) + 2 H_{2} O (g) \to C O_{2} (g) + 4 H C l (g),)$
we have
$△_{r} H = E n t h a l p y o f r e a c t i o n △_{f} H = E n t h a l p y o f f o r m a t i o n$
$△_{r} H = △_{f} H (C O_{2}, g) + 4 △_{f} H (H C l, g) - △_{F} H (C C l_{4}, l) - 2 △_{f} H (H_{2} O, g)$
Putting all the values, We get;
$△_{r} H = (- 394 - 4 \times 93 + 107 + 2 \times 242) k J m o l^{- 1} = - 175 k J m o l^{- 1}$
Also, We know;
$△ H = △ U + △ n_{g} R T$
where, $△ n_{g}$ is number of change in gaseous moles.
$△ U = △ H - △ n_{g} R T$
$△ n_{g} = 5 - 2 = 3$
putting this and other values in the formula above,
$△ U = △ H - △ n_{g} R T$
$= - 175 k J - (3 \times 8.3 \times 300 \times 10^{- 3} k J) = - 182.47 k J m o l^{- 1}$

Suggest Corrections

thumbs-up

0

Similar questions

Q. The standard enthalpies of formation at 300 K for

C C l_{4} (l), H_{2} O (g), C O_{2} (g) a n d H C l (g) a r e - 107, - 242, - 394 a n d - 93 k J m o l^{- 1},

respectively. The value of

△ U_{300}^{o}

for the reaction:

C C l_{4} (l) + 2 H_{2} O (g) \to C O_{2} (g) + 4 H C l (g)

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

. Find the value of

x

R = 8.314 J K^{- 1} m o l^{- 1}

Q. The standard enthalpies of formation at

300 K

C C l_{4} (l), H_{2} O (g), C O_{2} (g)

H C l (g)

- 107, - 242, - 394

- 93 {kJ mol}^{- 1}

respectively. The value of

Δ U

for the following reaction at

300 K

C C l_{4} (l) + 2 H_{2} O (g) \to C O_{2} (g) + 4 H C l (g)

Q. The standard enthalpies of formation at 300 K for

C C l_{4} (l), H_{2} O (g), (C O_{2}) a n d H C l (g) a r e - 107, - 242, - 394 a n d - 93 k J m o l^{- 1},

respectively. The value of

△ U_{300}^{o}

for the reaction

C C l_{4} (l) + 2 H_{2} O (g) \to C O_{2} (g) + 4 H C l (g)

Q. The standard enthalpies of formation at 300 K for

C C l_{4} (l), H_{2} O (g), C O_{2} (g) a n d H C l (g)

are -107, -242, -394, and -93

k J m o l^{- 1}

respectively. The value of

Δ U

for the reaction

C C l_{4} (l) + 2 H_{2} O (g) \to C O_{2} (g) + 4 H C l (g)

Q. The standard enthalpy of formation of octane

(C_{8} H_{18})

- 250 k J / m o l

. Calculate the enthalpy of combustion of

C_{8} H_{18}

.
Given : enthalpy of formation of

C O_{2} (g)

H_{2} O (l)

- 394 k J / m o l

- 286 k J / m o l

View More

Join BYJU'S Learning Program

similar_icon

Related Videos

lock

CHEMISTRY

Watch in App

explore_more_icon

Explore more

Internal Energy

Standard XI Chemistry

Join BYJU'S Learning Program

CrossIcon