(D) The given reactions are:$1$) $H_{2(g)} + \frac{1}{2}O_{2(g)} \rightarrow H_2O_{(l)}$; $\Delta H_1 = -68.32 \, kcal$$2$) $H_2O_{(l)} \rightarrow H_

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(D) The given reactions are:$1$) $H_{2(g)} + \frac{1}{2}O_{2(g)} \rightarrow H_2O_{(l)}$; $\Delta H_1 = -68.32 \, kcal$$2$) $H_2O_{(l)} \rightarrow H_2O_{(g)}$; $\Delta H_2 = 10.52 \, kcal$Adding these two equations gives the formation reaction for water vapor:$H_{2(g)} + \frac{1}{2}O_{2(g)} \rightarrow H_2O_{(g)}$Applying Hess's Law:$\Delta H_f(H_2O_{(g)}) = \Delta H_1 + \Delta H_2$$\Delta H_f(H_2O_{(g)}) = -68.32 + 10.52 = -57.8 \, kcal$

Class 11 Chemistry Thermodynamics Heat of reaction, Bond energy and Hess law

Medium

$H_{2(g)} + \frac{1}{2}O_{2(g)} \rightarrow H_2O_{(l)}$; $\Delta H_{298K} = -68.32 \, kcal$. The enthalpy of vaporization of water at $25 \, ^\circ C$ and $1 \, atm$ pressure is $10.52 \, kcal$. Calculate the standard enthalpy of formation of $1 \, mole$ of water vapor at $25 \, ^\circ C$ (in $kcal$).

A
$10.52$
B
$-78.84$
C
$57.8$
D
$-57.8$

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Class 11 Questions

Class 11

Chemistry Questions

Chapter

Thermodynamics

Subtopic

Heat of reaction, Bond energy and Hess law

Average $C-H$ bond energy is $416 \ kJ \ mol^{-1}$. Which of the following is correct?

MediumAP EAMCET 2004

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Consider the following processes:

Process $\Delta H \ (kJ/mol)$

$I. \ \frac{1}{2} A \rightarrow B$ $+150$

$II. \ 3B \rightarrow 2C + D$ $-125$

$III. \ E + A \rightarrow 2D$ $+350$

For $B + D \rightarrow E + 2C, \Delta H$ will be ............. $kJ/mol$

Process	$\Delta H \ (kJ/mol)$
$I. \ \frac{1}{2} A \rightarrow B$	$+150$
$II. \ 3B \rightarrow 2C + D$	$-125$
$III. \ E + A \rightarrow 2D$	$+350$

MediumAIPMT 2011

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The bond dissociation enthalpy of $H_{2(g)}$ and $N_{2(g)}$ are $436 \ kJ \ mol^{-1}$ and $940 \ kJ \ mol^{-1}$ respectively,and the enthalpy of formation of $NH_{3(g)}$ is $-45 \ kJ \ mol^{-1}$. The enthalpy of atomisation of $NH_{3(g)}$ is ..... $kJ \ mol^{-1}$.

Difficult

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The molar enthalpies of combustion of $C_2H_{2(g)},$ $C$ (graphite) and $H_{2(g)}$ are $-1300,$ $-394$ and $-286 \ kJ \ mol^{-1},$ respectively. The standard enthalpy of formation of $C_2H_{2(g)}$ is.......$kJ \ mol^{-1}$

Medium

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From the following data,the heat of transition for the conversion of rhombic sulfur $(S_R)$ to monoclinic sulfur $(S_M)$ in $kJ$ is:
$S_R + O_{2(g)} \to SO_{2(g)}; \Delta H = -296.90 \ kJ$
$S_M + O_{2(g)} \to SO_{2(g)}; \Delta H = -299.40 \ kJ$

Difficult

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Average $C-H$ bond energy is $416 \ kJ \ mol^{-1}$. Which of the following is correct?

Consider the following processes: Process $\Delta H \ (kJ/mol)$ $I. \ \frac{1}{2} A \rightarrow B$ $+150$ $II. \ 3B \rightarrow 2C + D$ $-125$ $III. \ E + A \rightarrow 2D$ $+350$ For $B + D \rightarrow E + 2C, \Delta H$ will be ............. $kJ/mol$

The bond dissociation enthalpy of $H_{2(g)}$ and $N_{2(g)}$ are $436 \ kJ \ mol^{-1}$ and $940 \ kJ \ mol^{-1}$ respectively,and the enthalpy of formation of $NH_{3(g)}$ is $-45 \ kJ \ mol^{-1}$. The enthalpy of atomisation of $NH_{3(g)}$ is ..... $kJ \ mol^{-1}$.

The molar enthalpies of combustion of $C_2H_{2(g)},$ $C$ (graphite) and $H_{2(g)}$ are $-1300,$ $-394$ and $-286 \ kJ \ mol^{-1},$ respectively. The standard enthalpy of formation of $C_2H_{2(g)}$ is.......$kJ \ mol^{-1}$

From the following data,the heat of transition for the conversion of rhombic sulfur $(S_R)$ to monoclinic sulfur $(S_M)$ in $kJ$ is:$S_R + O_{2(g)} \to SO_{2(g)}; \Delta H = -296.90 \ kJ$$S_M + O_{2(g)} \to SO_{2(g)}; \Delta H = -299.40 \ kJ$

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Consider the following processes:

Process $\Delta H \ (kJ/mol)$

$I. \ \frac{1}{2} A \rightarrow B$ $+150$

$II. \ 3B \rightarrow 2C + D$ $-125$

$III. \ E + A \rightarrow 2D$ $+350$

For $B + D \rightarrow E + 2C, \Delta H$ will be ............. $kJ/mol$

From the following data,the heat of transition for the conversion of rhombic sulfur $(S_R)$ to monoclinic sulfur $(S_M)$ in $kJ$ is:
$S_R + O_{2(g)} \to SO_{2(g)}; \Delta H = -296.90 \ kJ$
$S_M + O_{2(g)} \to SO_{2(g)}; \Delta H = -299.40 \ kJ$