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Calculate the electron affinity of fluorine atom (in $kJ {mol}^{- 1}$ ) using the following data. Make Born-Haber's cycle. All the values are in $kJ {mol}^{- 1}$ at $25^{°} C, ∆ H_{diss} (F_{2}) = 160 kJ {mol}^{- 1}, ∆ H_{f}^{°} (NaF (s)) = - 571 kJ {mol}^{- 1} . I . E . [Na (g)] = 494 kJ {mol}^{- 1}$ , $∆ H_{vap} = [Na (s)] = 101 kJ {mol}^{- 1}$ . Lattice energy of $NaF (s) = - 894$ $kJ {mol}^{- 1}$ .

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Important Questions on Thermodynamics

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Beta Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>EXERCISE-3>Q 56

Cesium chloride is formed according to the following equation :

$Cs (s) + 0.5 {Cl}_{2} (g) \to CsCl (s)$ .

The enthalpy of sublimation of $Cs$ , enthalpy of dissociation of chloride, ionization energy of $Cs$ & electron affinity of chlorine are $81.2, 243.0, 375, 7$ and $- 348.3 kJ {mol}^{- 1}$ . The energy change involved in the formation of $CsCl$ is $- 388.6 kJ {mol}^{- 1}$ . Calculate the lattice energy of $CsCl$ . (in $kJ {mol}^{- 1}$ ) enolved.

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Beta Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>EXERCISE-3>Q 57

The enthalpy of formation of ethane, ethylene and benzene from the gaseous atom are

- 2839.2, - 2275.2

and

- 5506 kJ {mol}^{- 1}

respectively. Calculate the modulus of resonance energy of benzene (in

kJ {mol}^{- 1}

). The bond enthalpy of

C - H

bond is given as equal to

+ 410.87 kJ / mol

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Beta Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>EXERCISE-3>Q 58

Two mole of ideal diatomic gas

(C_{V, m} = 5 / 2 R)

300 K

and

5 atm

expanded irreversibly & adiabatically to a final pressure of

2 atm

against a constant pressure of

1 atm

. Calculate

∆ H

(in

J

)

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Beta Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>EXERCISE-3>Q 59

A bomb calorimeter containing

5.4 g

Al

and

15.97 g

{Fe}_{2} O_{3}

is placed in an ice calorimeter containing initially

8 kg

of ice and

8 kg

of water. The reaction

2 Al (s) + {Fe}_{2} O_{3} (s) \to {Al}_{2} O_{3} (s) + 2 Fe (s)

is set off by remote control and it is then observed that the calorimeter contains

7.746 kg

of ice and

8.254 kg

of water. Find the

∆ H

for the above reaction. (in kcal)

$∆ H_{fussion} (ice) = 1.436 kcal / mole$

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Beta Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>EXERCISE-3>Q 60

A sample of the sugar D-ribose $(C_{5} H_{10} O_{5})$ of mass $0.727 g$ was placed in a calorimeter and then ignited in the presence of excess oxygen. The temperature was raised by $0.910 K$ . In a separate experiment in the same calorimeter, the combustion of $0.825 g$ of benzoic acid, for which the internal energy of combustion is $- 3251 kJ {mol}^{- 1}$ , gave a temperature rise of $1.940 K$ . Calculate the internal energy of combustion of D-ribose in $kJ {mol}^{- 1}$ . Give answer in 2 decimal places.

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Beta Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>EXERCISE-3>Q 61

The heat of combustion of

{formaldehyde}_{(g)}

- 134 kcal {mole}^{- 1}

and the heat of combustion of

{paraformaldehyde}_{(s)}

- 122 kcal per (1 / n) {({CH}_{2} O)}_{n}

. Calculate the heat of polymerization of formaldehyde to paraformaldehyde in

kJ {mol}^{- 1}

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Beta Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>EXERCISE-3>Q 62

The disaccharide

α

-maltose can be hydrolysed to glucose according to the equation

C_{12} H_{22} O_{11} (aq) + H_{2} O (l) \to 2 C_{6} H_{12} O_{6} (aq)

Using the following values, calculate the standard enthalpy change of the above reaction in $kJ {mol}^{- 1}$ .

$∆_{f} H^{°} (H_{2} O, l) = - 285.85 kJ \cdot {mol}^{- 1}$

$∆_{f} H^{°} (C_{6} H_{12} O_{6}, aq) = - 1263.1 kJ \cdot {mol}^{- 1}$

$∆_{f} H^{°} (C_{12} H_{22} O_{11}, aq) = - 2238.3 kJ \cdot {mol}^{- 1}$

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Beta Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>EXERCISE-3>Q 63

For an ionic solid

{MX}_{2}

, where

X

is monovalent, the enthalpy, the enthalpy of formation of the solid from

M (s)

and

X_{2} (g)

1.5

times the electron gain enthalpy of

X (g)

. The first and second ionisation enthalpies of the metal

(M)

are

1.2

and

2.8

times of the enthalpy of sublimation of

M (s)

. The bond dissociation enthalpy of

X_{2} (g)

0.8

times the first ionisation enthalpy of metal and it is also equal to one-fifth of the magnitude of lattice enthalpy of

{MX}_{2}

. If the electron gain enthalpy of

X (g)

- 96 Kcal / mol

, then answer the enthalpy of sublimation of metal

(M)

Kcal / mol

Calculate the electron affinity of fluorine atom (in kJ mol-1) using the following data. Make Born-Haber's cycle. All the values are in kJ mol-1 at 25°C, ∆HdissF2=160 kJ mol-1, ∆Hf° NaFs=-571 kJ mol-1.I.E. Nag=494 kJ mol-1, ∆Hvap=Nas=101kJ mol-1. Lattice energy of NaFs=-894 kJ mol-1.

Important Questions on Thermodynamics

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