JEE Main 2023 — Chemistry Physical Chemistry

2023integermedium

Solid fuel used in rocket is a mixture of ${\mathrm{Fe}}_{2}{O}_{3}$ and $\mathrm{Al}$ (in ratio $1:2$ ). The heat evolved $(\mathrm{kJ})$ per gram of the mixture is _____ (Nearest integer)

Given ${\Delta H}_{f}^{0}({\mathrm{Al}}_{2}{O}_{3})=-1700\mathrm{kJ}{\mathrm{mol}}^{-1}$

${\Delta H}_{f}^{0}({\mathrm{Fe}}_{2}{O}_{3})=-840\mathrm{kJ}{\mathrm{mol}}^{-1}$

Molar mass of $\mathrm{Fe},\mathrm{AI}$ and $O$ are $56,27$ and $16g{\mathrm{mol}}^{–1}$ respectively

Official previous-year question

Held on 11 Apr 2023 · Verified 6 Jul 2026.

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Solution

Molten iron can be prepared by alumino thermite process as shown below.

${\mathrm{Fe}}_{2}{O}_{3}+2\mathrm{Al}\rightarrow 2\mathrm{Fe}+{\mathrm{Al}}_{2}{O}_{3}$

The iron oxide and aluminium metal ratio is $1:2$ in the above reaction.

Now, the Enthalpy of the reaction is equal to the difference of enthalpy of formation of products to the enthalpy of formation of reactants.

${\Delta H}_{\text{reaction }}^{0}=-1700+(840)$

Ratio of ${\mathrm{Fe}}_{2}{O}_{3}$ and $\mathrm{Al}$

$=160:54$

$=2.96\mathrm{in}214\mathrm{gm}$ mixture

$\therefore \frac{\Delta H^{\circ}}{1\mathrm{gm}\text{ mixture }}=\frac{-860}{214}=-4\mathrm{kJ}/\mathrm{gram}$

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JEE Main 2023 — Chemistry Physical Chemistry

2023integermedium

Solid fuel used in rocket is a mixture of ${\mathrm{Fe}}_{2}{O}_{3}$ and $\mathrm{Al}$ (in ratio $1:2$ ). The heat evolved $(\mathrm{kJ})$ per gram of the mixture is _____ (Nearest integer)

Given ${\Delta H}_{f}^{0}({\mathrm{Al}}_{2}{O}_{3})=-1700\mathrm{kJ}{\mathrm{mol}}^{-1}$

${\Delta H}_{f}^{0}({\mathrm{Fe}}_{2}{O}_{3})=-840\mathrm{kJ}{\mathrm{mol}}^{-1}$

Molar mass of $\mathrm{Fe},\mathrm{AI}$ and $O$ are $56,27$ and $16g{\mathrm{mol}}^{–1}$ respectively

Official previous-year question

Held on 11 Apr 2023 · Verified 6 Jul 2026.

Did you get this right?

Solution

Molten iron can be prepared by alumino thermite process as shown below.

${\mathrm{Fe}}_{2}{O}_{3}+2\mathrm{Al}\rightarrow 2\mathrm{Fe}+{\mathrm{Al}}_{2}{O}_{3}$

The iron oxide and aluminium metal ratio is $1:2$ in the above reaction.

Now, the Enthalpy of the reaction is equal to the difference of enthalpy of formation of products to the enthalpy of formation of reactants.

${\Delta H}_{\text{reaction }}^{0}=-1700+(840)$

Ratio of ${\mathrm{Fe}}_{2}{O}_{3}$ and $\mathrm{Al}$

$=160:54$

$=2.96\mathrm{in}214\mathrm{gm}$ mixture

$\therefore \frac{\Delta H^{\circ}}{1\mathrm{gm}\text{ mixture }}=\frac{-860}{214}=-4\mathrm{kJ}/\mathrm{gram}$

JEE Main 2023 — Chemistry Physical Chemistry

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Solution

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JEE Main 2023 — Chemistry Physical Chemistry

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry