The following two reactions are known aligned & Fe_ 2 O_ 3 (~s)+3 CO(g) 2 Fe(s)+3 CO_ 2 ( ~g), & Δ H=-26.8 ~kJ & FeO(s)+CO(g) Fe(s)+CO_ 2 (~g) & Δ H=-16.5 ~kJ aligned The value of Δ H for the following reaction Fe_2

Correct answer: D. +6.2 ~kJ Given, (I) Fe_2 O_3( s)+3 CO(g) 2 Fe(s)+3 CO_2( g) ; Δ H=-26.8 kJ (II) FeO (s) +CO(g) Fe(s)+CO_2( g) ; Δ H=-16.5 kJ On multiplying Eq (II) with 2, we get (III) 2 FeO(s)+2 CO(g) 2 Fe(s)+2 CO_2( g) ; Δ H=-33 kJ On subtracting Eq (III) from I, we get array r Fe_ 2 O _ 3 ( s)+CO(g) 2 FeO(s)+CO _ 2 ( g); Δ H=-26.8-(-33) =+6.2 kJ array

NEET 2010

Exam: NEET
Year: 2010
Subject: Chemistry
Chapter: Thermodynamics (C)

NEET 2010 · Chemistry · Thermodynamics (C)

The following two reactions are known aligned & Fe_ 2 O_ 3 (~s)+3...

The following two reactions are known

\begin{aligned}& \mathrm{Fe}_{2} \mathrm{O}_{3}(\mathrm{~s})+3 \mathrm{CO}(\mathrm{g}) \longrightarrow2 \mathrm{Fe}(\mathrm{s})+3 \mathrm{CO}_{2}( \mathrm{~g}),\\ & \Delta \mathrm{H}=-26.8 \mathrm{~kJ}\\ & \mathrm{FeO}(\mathrm{s})+\mathrm{CO}(\mathrm{g}) \longrightarrow \mathrm{Fe}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{~g})\\ & \Delta \mathrm{H}=-16.5 \mathrm{~kJ} \end{aligned}

The value of

\Delta \mathrm{H}

for the following reaction

\mathrm{Fe}_2 \mathrm{O}_3(\mathrm{~s})+\mathrm{CO}(\mathrm{g}) \longrightarrow 2 \mathrm{FeO}(\mathrm{s})+\mathrm{CO}_2(\mathrm{~g})

Options

A $+10.3 \mathrm{~kJ}$
B $-43.3 \mathrm{~kJ}$
C $-10.3 \mathrm{~kJ}$
D $+6.2 \mathrm{~kJ}$

Correct answer

D. $+6.2 \mathrm{~kJ}$

Step-by-step solution

Given, (I)

\mathrm{Fe}_2 \mathrm{O}_3(\mathrm{ s})+3 \mathrm{CO}(\mathrm{g}) \longrightarrow 2 \mathrm{Fe}(\mathrm{s})+3 \mathrm{CO}_2(\mathrm{ g})

;

\Delta \mathrm{H}=-26.8 \mathrm{ kJ}

(II)

\mathrm{FeO}

(s)

+\mathrm{CO}(\mathrm{g}) \longrightarrow \mathrm{Fe}(\mathrm{s})+\mathrm{CO}_2(\mathrm{ g})

;

\Delta \mathrm{H}=-16.5 \mathrm{ kJ}

On multiplying Eq (II) with 2, we get (III)

2 \mathrm{FeO}(\mathrm{s})+2 \mathrm{CO}(\mathrm{g}) \longrightarrow 2 \mathrm{Fe}(\mathrm{s})+2 \mathrm{CO}_2(\mathrm{ g})

;

\Delta \mathrm{H}=-33 \mathrm{ kJ}

On subtracting Eq (III) from I, we get

\begin{array}{r}\mathrm{Fe}_{2} \mathrm{O}}_{3}(\mathrm{ s})+\mathrm{CO}(\mathrm{g}) \longrightarrow2 \mathrm{FeO}(\mathrm{s})+\mathrm{CO}}_{2}(\mathrm{ g}); \\ \Delta \mathrm{H}=-26.8-(-33) \\ =+6.2 \mathrm{ kJ} \end{array}

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