The enthalpies of formation of Al2O3 and Cr2O3 are -1569 KJ and -1134 KJ respectively- - H for the reaction 2Al - Cr2O3 - 2Cr - Al2O3 is

2Al + 3/2O_2 → Al_2O_3 Δ H = 1596 KJ ...............(i) 2Cr + 3/2O_2 → Cr_2O_3, Δ H = 1134 KJ ................(ii) By (i) (ii) 2Al + Cr_2O_3 → 2Cr + Al_2 ...

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Standard XII

Chemistry

Hess' Law

The enthalpie...

Question

The enthalpies of formation of $A l_{2} O_{3}$ and $C r_{2} O_{3}$ are $- 1569 K J$ and $- 1134 K J$ respectively. $Δ H$ for the reaction

$2 A l + C r_{2} O_{3} \to 2 C r + A l_{2} O_{3}$ is

- 2730 K J

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- 462 K J

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- 1365 K J

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+ 2730 K J

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Solution

The correct option is B $- 462 K J$
$2 A l + \frac{3}{2} O_{2} \to A l_{2} O_{3} Δ H = - 1596 K J$ ...............(i)

$2 C r + \frac{3}{2} O_{2} \to C r_{2} O_{3}, Δ H = - 1134 K J$ ................(ii)

By (i) - (ii)

$2 A l + C r_{2} O_{3} \to 2 C r + A l_{2} O_{3}, Δ H = - 462 K J$

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Similar questions

Q. The enthalpies of formation of

A l_{2} O_{3}

and

C r_{2} O_{3}

are -1596 kJ and -1134 kJ respectively.

Δ H

for the reaction,

2 A l + C r_{2} O_{3} \to 2 C r + A l_{2} O_{3}

is :

The enthalpies of formation of $A l_{2} O_{3}$ and $C r_{2} O_{3}$ are $- 1569 K J$ and $- 1134 K J$ respectively. $Δ H$ for the reaction

$2 A l + C r_{2} O_{3} \to 2 C r + A l_{2} O_{3}$ is

Q. When

10 g

A l

is used for reduction in each of the following alumino thermic reactions, which reaction would generate more heat and by how much ?
a.

2 A l + C r_{2} O_{3} \to A l_{2} O_{3} + 2 C r

2 A l + F e_{2} O_{3} \to A l_{2} O_{3} + 2 F e

Standard heat of formation of

A l_{2} O_{3}

C r_{2} O_{3}

and

F e_{2} O_{3}

are

- 1676 k J

- 1141 k J

and

- 822.2 k J

, respectively.

Q. For the formation of

C r_{2} O_{3}

and

A l_{2} O_{3}

, values of

Δ_{f} G^{o}

are 540 kJ mol

^{- 1}

and -827 kJ mol

^{- 1}

respectively. What will be the possibility for reaction of

C r_{2} O_{3}

by Al?

Q. In the reaction:

2 A l + C r_{2} O_{3} \to A l_{2} O_{3} + 2 C r

4.98

g of

A l

reacted with

20.0

C r_{2} O_{3}

. How much grams of reactant remains at the completion of the reaction?

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The enthalpies of formation of Al2O3 and Cr2O3 are −1569 KJ and −1134 KJ respectively. ΔH for the reaction 2Al + Cr2O3 → 2Cr + Al2O3 is

The correct option is B −462 KJ2Al + 32O2 → Al2O3 ΔH = −1596KJ ...............(i) 2Cr + 32O2 → Cr2O3, ΔH = −1134KJ ................(ii) By (i) - (ii) 2Al + Cr2O3 → 2Cr + Al2O3, ΔH = −462KJ

The enthalpies of formation of $A l_{2} O_{3}$ and $C r_{2} O_{3}$ are $- 1569 K J$ and $- 1134 K J$ respectively. $Δ H$ for the reaction

$2 A l + C r_{2} O_{3} \to 2 C r + A l_{2} O_{3}$ is

The correct option is B $- 462 K J$
$2 A l + \frac{3}{2} O_{2} \to A l_{2} O_{3} Δ H = - 1596 K J$ ...............(i)

$2 C r + \frac{3}{2} O_{2} \to C r_{2} O_{3}, Δ H = - 1134 K J$ ................(ii)

By (i) - (ii)

$2 A l + C r_{2} O_{3} \to 2 C r + A l_{2} O_{3}, Δ H = - 462 K J$