The surface of copper gets tarnished by the formation of copper oxide. $N_{2}$ gas was passed to prevent the oxide formation during heating of copper at 1250 K. However, the $N_{2}$ gas contains 1 mole % of water vapour as impurity. The water vapour oxidises copper as per the reaction given below:

$2 C u (s) + H_{2} O (g) \to C u_{2} O (s) + H_{2} (g)$

$P_{H_{2}}$ Is the minimum partial pressure of $H_{2}$ (in bar) needed to prevent the oxidation at 1250 K. The value of $\ln (p H_{2})$ is ____.

(Given: total pressure $=1$ bar, R (universal gas constant) $=8 J K ^{-1} mol^{-1}, \ln (10) =2.3 \cdot Cu (s)$ and $Cu _2 O (s)$ are mutually immiscible.

At $1250 K: 2 Cu ( s )+\frac{1}{2} O _2(g) \rightarrow Cu _2 O ( s ) ;$ $\Delta G^{\ominus}=-78,000 J mol ^{-1}$

$H _2(g)+\frac{1}{2} O _2(g) \rightarrow H _2 O ( g ) ; \quad \Delta^{\ominus}=$$-1,78,000 J mol ^{-1} ; G$ is the Gibbs energy)/mi> $\Theta=$ $-78,000 J mol -1$

$H _2(g)+\frac{1}{2} O _2(g) \rightarrow H _2 O ( g ) ; \quad$$\Delta^{\ominus}=-1,78,000 J mol ^{-1} ; G$ is the Gibbs energy)

Question

The surface of copper gets tarnished by the formation of copper oxide.

N_{2}

gas was passed to prevent the oxide formation during heating of copper at 1250 K. However, the

N_{2}

gas contains 1 mole % of water vapour as impurity. The water vapour oxidises copper as per the reaction given below:

2 C u (s) + H_{2} O (g) \to C u_{2} O (s) + H_{2} (g)

P_{H_{2}}

Is the minimum partial pressure of

H_{2}

(in bar) needed to prevent the oxidation at 1250 K. The value of

\ln (p H_{2})

is ____.

(Given: total pressure $=1$ bar, R (universal gas constant) $=8 J K ^{-1} mol^{-1}, \ln (10) =2.3 \cdot Cu (s)$ and $Cu _2 O (s)$ are mutually immiscible.

At $1250 K: 2 Cu ( s )+\frac{1}{2} O _2(g) \rightarrow Cu _2 O ( s ) ;$ $\Delta G^{\ominus}=-78,000 J mol ^{-1}$

$H _2(g)+\frac{1}{2} O _2(g) \rightarrow H _2 O ( g ) ; \quad \Delta^{\ominus}=$$-1,78,000 J mol ^{-1} ; G$ is the Gibbs energy)/mi> $\Theta=$ $-78,000 J mol -1$

$H _2(g)+\frac{1}{2} O _2(g) \rightarrow H _2 O ( g ) ; \quad$$\Delta^{\ominus}=-1,78,000 J mol ^{-1} ; G$ is the Gibbs energy)

Accepted Answer

(A) 14.6

Answer

(B) 14.52

Answer

(C) 14.55

Answer

(D) 14.2

	List-I		List-II
A.	Volume of parallelepiped determined by vectors $\vec{a}, \vec{b}$ and $\vec{c}$ is $2$ . Then the volume of the parallelepiped determined by vectors $2 (\vec{a} \times \vec{b}), 3 (\vec{b} \times \vec{c})$ and $(\vec{c} \times \vec{a})$ is	P.	$100$
B.	Volume of parallel piped determined by vectors $\vec{a}, \vec{b}$ and $\vec{c}$ is $5$ . Then the volume of the parallelepiped determined by vectors $3 (\vec{a} + \vec{b}), (\vec{b} + \vec{c})$ and $2 (\vec{c} + \vec{a})$ is	Q.	$30$
C	Area of a triangle with adjacent sides determined by vectors $\vec{a}$ and $\vec{b}$ is $20$ .Then the area of the triangle with adjacent sides determined by vectors $(2 \vec{a} + 3 \vec{b})$ and $(\vec{a} - \vec{b})$ is	R.	$24$
D	Area of a parallelogram with adjacent sides determined by vectors $\vec{a}$ and $\vec{b}$ is $30$ . Then the area of the parallelogram with adjacent sides determined by vectors $(\vec{a} + \vec{b})$ and $\vec{a}$ is	S.	$60$

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