Enthalpy of polymerisation of ethylene, as represented by the reaction, nCH 2 = CH 2 ⟶ - CH 2 - CH 2 - n is - 100 kJ per mole of ethylene. Given bond enthalpy of C = C bond is 600 kJ mol - 1 , determine enthalpy of C - C bond (in kJ mol ).

nCH 2 = CH 2 ⟶ - CH 2 - CH 2 - n ΔH = - 100 KJ / mole Double bond of ethylene converted to two single bonds. ΔH = - 100 = B . E . C = C - 2 B . E . C - C ⇒ - 100 = 600 - 2 × B . E . c - c ⇒ B . E . C - C = 350 KJ / mole .

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An athlete is given $100 g$ of glucose $(C_{6} H_{12} O_{6})$ of energy equivalent to $1560 kJ$ . He utilises $50$ percent of this gained energy in the event. In order to avoid storage of energy in the body, determine the weight of water he would need to perspire. (The enthalpy of evaporation of water is $44 kJ / mole$ ).

Important Questions on Thermodynamics & Thermochemistry

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Practice Book for KVPY Aptitude Test - Stream SA Chemistry>Chapter 5 - Thermodynamics & Thermochemistry>EXERCISE>Q 42

From the following data, determine the enthalpy change for the sublimation of ice at

223 K

. [Mean heat capacity of ice

= 2 {JK}^{- 1} {gm}^{- 1}

, mean heat capacity of

H_{2} O (l) = 4.2 {JK}^{- 1} {gm}^{- 1}

, mean heat capacity of

H_{2} O (g) = 1.85 {JK}^{- 1} {gm}^{- 1}

, enthalpy of fusion of ice at

0 ° C = 334 J {gm}^{- 1}

, enthalpy of evaporation of water at

100 ° C = 2255 J {gm}^{- 1}

]

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Practice Book for KVPY Aptitude Test - Stream SA Chemistry>Chapter 5 - Thermodynamics & Thermochemistry>EXERCISE>Q 43

The heat of formation of

C_{2} H_{5} OH (l)

- 66 kcal / mole

. The heat of combustion of

{CH}_{3} {OCH}_{3} (g)

- 348 kcal / mole . ∆ H_{f}

for

H_{2} O

and

{CO}_{2}

are

- 68 kcal / mole

and

- 94 kcal / mole

respectively. Then determine the

ΔH

for the isomerisation reaction

C_{2} H_{5} OH (l) ⟶ {CH}_{3} {OCH}_{3} (g)

, and

ΔE

for the same are at

T = 25 ° C

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Practice Book for KVPY Aptitude Test - Stream SA Chemistry>Chapter 5 - Thermodynamics & Thermochemistry>EXERCISE>Q 44

In the reaction,

{AB}_{2} (l) + 3 X_{2} (g) ⇌ {AX}_{2} (g) + 2 {BX}_{2} (g) ΔH = - 270 kcal per mol

{AB}_{2} (l)

, the enthalpies of formation of

{AX}_{2} (g) & {BX}_{2} (g)

are in the ratio of

4 : 3

and have opposite sign. Determine the value of

{ΔH}_{f}^{0} ({AB}_{2} (l)) = + 30 Kcal / mole

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Practice Book for KVPY Aptitude Test - Stream SA Chemistry>Chapter 5 - Thermodynamics & Thermochemistry>EXERCISE>Q 45

AB, A_{2}

and

B_{2}

are diatomic molecules. If the bond enthalpies of

A_{2}, AB & B_{2}

are in the ratio

1 : 1 : 0.5

and enthalpy of formation of

AB

from

A_{2}

and

B_{2}

- 100 kJ / {mol}^{- 1}

. What is the bond enthalpy of

A_{2}

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Practice Book for KVPY Aptitude Test - Stream SA Chemistry>Chapter 5 - Thermodynamics & Thermochemistry>EXERCISE>Q 46

When a certain amount of ethylene was combusted,

6226 kJ

heat was evolved. If heat of combustion of ethylene is

1411 kJ

, determine the volume of

O_{2}

(at

NTP

) that entered into the reaction.

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Practice Book for KVPY Aptitude Test - Stream SA Chemistry>Chapter 5 - Thermodynamics & Thermochemistry>EXERCISE>Q 47

Given the following reactions:

I: $N_{2} (g) + 2 O_{2} (g) ⟶ 2 {NO}_{2} (g), {ΔH}_{I} = 16.18 kcal$

II: $N_{2} (g) + 2 O_{2} (g) ⟶ N_{2} O_{4} (g), {ΔH}_{II} = 2.31 kcal$

Which amongst ${NO}_{2} (g)$ and $N_{2} O_{4} (g)$ is more stable?

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Practice Book for KVPY Aptitude Test - Stream SA Chemistry>Chapter 5 - Thermodynamics & Thermochemistry>EXERCISE>Q 48

Enthalpy of polymerisation of ethylene, as represented by the reaction,

{nCH}_{2} = {CH}_{2} ⟶ {(- {CH}_{2} - {CH}_{2} -)}_{n}

- 100 kJ

per mole of ethylene. Given bond enthalpy of

C = C

bond is

600 kJ {mol}^{- 1}

, determine enthalpy of

C - C

bond (in

kJ mol

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Practice Book for KVPY Aptitude Test - Stream SA Chemistry>Chapter 5 - Thermodynamics & Thermochemistry>EXERCISE>Q 49

Substance $A_{2} B (g)$ can undergo decomposition to form two sets of products:

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If the molar ratio of $A_{2} (g)$ to $A (g)$ is $5 : 3$ in a set of product gases, determine then the energy involved in the decomposition of $1$ mole of $A_{2} B$ .

An athlete is given 100 g of glucose C6H12O6 of energy equivalent to 1560 kJ. He utilises 50 percent of this gained energy in the event. In order to avoid storage of energy in the body, determine the weight of water he would need to perspire. (The enthalpy of evaporation of water is 44 kJ/mole).

Important Questions on Thermodynamics & Thermochemistry

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