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Naya [18.7K]
3 years ago
13

In the following overall chemical reaction, aluminum displaces chromium from chromium(III) oxide and forms aluminum oxide.

Chemistry
1 answer:
mafiozo [28]3 years ago
6 0

Answer:

Change in enthalpy for the reaction is -536 kJ

Explanation:

  • Overall chemical reaction can be represented a summation of two given elementary steps with slight modification.
  • Take reaction (1a) and divide stoichiometric coefficients by 2
  • Take reverse reaction (2a) and divide stoichiometric coefficient by 2
  • Then add these two modified elementary steps to get overall chemical reaction
  • \Delta H is an additive property. hence value of \Delta H will be changed in accordance with modification

2Al+\frac{3}{2}O_{2}\rightarrow Al_{2}O_{3}.....\Delta H_{1}=\frac{-3351.4}{2}kJ=-1675.7kJ

Cr_{2}O_{3}\rightarrow 2Cr+\frac{3}{2}O_{2}....\Delta H_{2}=\frac{2279.4}{2}kJ=1139.7kJ

--------------------------------------------------------------------------------------------------------------

2Al+Cr_{2}O_{3}\rightarrow 2Cr+Al_{2}O_{3}....\Delta H=\Delta H_{1}+\Delta H_{2}=-1675.7+1139.7kJ=-536kJ

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