Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 161

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The values of heat of combustion of ethane $(C_{2} H_{6})$ and ethyne $(C_{2} H_{2})$ are $- 341$ and $- 310 Kcal$ respectively. Then which of the following is better fuel on a mass basis:

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Important Questions on Thermodynamics

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 162

If enthalpy of dissociation of

{CH}_{4}

and

C_{2} H_{6}

are

320

and

600

calories respectively then bond energy of

C - C

bond is:

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 163

The bond dissociation energy of gaseous

H_{2}, {Cl}_{2}

and

HCl

are

104, 58

and

103 kcal {mol}^{- 1}

respectively. The enthalpy of formation for

HCl

gas will be:

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 164

AB, A_{2}

and

B_{2}

are diatomic molecules. If the bond enthalpies of

A_{2}, AB

and

B_{2}

are in the ratio

1 : 1 : 0.5

and enthalpy of formation of

AB

from

A_{2}

and

B_{2}

is

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

What is the bond enthalpy of

A_{2} .

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 165

One mole of anhydrous

{MgCl}_{2}

dissolves in water and librates

25 {cal}^{- 1} mol

of heat.

{ΔH}_{hydration}

of

{MgCl}_{2} = - 30 {cal}^{- 1} mol .

Heat of dissolution of

{MgCl}_{2} \cdot H_{2} O

is:

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 166

Enthalpy of solution of

NaOH

(solid) in water is

- 41.6 k J m o l^{- 1}

. When

NaOH

is dissolved in water, the temperature of water

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 167

The enthalpy change for the reaction of

5

litres of ethylene with

5

litres of

H_{2}

gas at

1.5

atm

pressure is

ΔH = - 0.5 kJ .

The value of

ΔU

will be:

(1 atm Lt = 100 J)

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 168

For which one of the following reactions does the molar enthalpy change of a reaction corresponds to the lattice energy of

KBr ?

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Alpha Question Bank for Engineering: Chemistry>Chapter 4 - Thermodynamics>Exercise-1>Q 169

Calculate the lattice energy for the reaction:

${Li}^{+} (g) + Cr (g) ⟶ LiCl (s)$

Given that:

${ΔH}_{sub} (Li) = 160; {ΔH}_{diss} ({Cl}_{2}) = 244; IP (Li) = 520;$

$E_{A} (Cl) = - 365$ and ${ΔH}_{f} (LiCl) = - 400$ (all in $kJ {mole}^{- 1}$ )