3 . 5 g of a fuel (with molecular weight 28 g ), was burnt in a calorimeter which raised the temperature of 1 g water from 25 ° C to 67 . 3 ° C . If all the heat generated was used in heating water, calculate heat of combustion of fuel.

Heat exchanged during any process can be calculated as: Q = ms ∆ T Q = heat exchanged m = mass of substance s = specific heat of substance ∆ T = change in temperature Specific heat of the water s = 1 calg - 1 ° C - 1 So, the heat gained by the water during the rise of temperature from 25 ° C to 67 . 3 ° C is: Q = 1 × 1 × 67 . 3 - 25 = 42 . 3 cal The heat of combustion is defined as the heat released during the combustion of 1 mole of the substance in presence of a sufficient amount of the oxygen at given conditions. As, we know that the heat gained by the water is the heat generated from the burning of 3 . 5 g of the fuel. So, Q fuel = - Q water Q fuel = - 42 . 3 cal ∵ - 42 . 3 cal of heat is released by combustion of 3 . 5 g of fuel. Then, heat released by combustion of 1 mole i.e., 28 g of fuel will be = - 42 . 3 × 28 3 . 5 = - 338 . 4 calmol - 1 .

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In which of the following process does entropy increase?

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Important Questions on Thermodynamics

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IMPORTANT

Chapterwise/Topicwise Daily Practice Problems (DPP) Physical Chemistry Part 1 JEE Main & Advanced>Chapter 5 - Thermodynamics>DPP 5.5>Q 19

In which of the following reaction is

ΔS ° > 0

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Chapterwise/Topicwise Daily Practice Problems (DPP) Physical Chemistry Part 1 JEE Main & Advanced>Chapter 5 - Thermodynamics>DPP 5.5>Q 20

Which of the following represents the variation of $' G'$ correctly?

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Chapterwise/Topicwise Daily Practice Problems (DPP) Physical Chemistry Part 1 JEE Main & Advanced>Chapter 5 - Thermodynamics>DPP 5.5>Q 22

0 ° C,

if the enthalpy of fusion of ice is

1365 kcal / mol

, the molar entropy change for melting of ice at

0^{°} C

is …

kcal {mol}^{- 1} K^{- 1} .

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Chapterwise/Topicwise Daily Practice Problems (DPP) Physical Chemistry Part 1 JEE Main & Advanced>Chapter 5 - Thermodynamics>DPP 5.6>Q 1

A $1.250 g$ sample of octane ( $C_{8} H_{18}$ ) is burned in excess of oxygen in a bomb calorimeter. The temperature of the calorimeter rises from $294.05 K$ to $300.78 K$ . If the heat capacity of the calorimeter is $8.93 kJ / K$ , find the heat transferred to the calorimeter. Also, calculate the enthalpy of combustion of the sample of octane.

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Chapterwise/Topicwise Daily Practice Problems (DPP) Physical Chemistry Part 1 JEE Main & Advanced>Chapter 5 - Thermodynamics>DPP 5.6>Q 2

Calculate the enthalpy change on freezing $1.0 mol$ of water at $10.0 ° C$ to ice at $- 10.0 ° C$

$Δ_{fus} H = 6.03 {kJmol}^{- 1}$ at $0 ° C$

$C_{p} [H_{2} O (l)] = 75.3 J {mol}^{- 1} K^{- 1}$

$C_{p} [H_{2} O (s)] = 36.8 J {mol}^{- 1} K^{- 1}$

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Chapterwise/Topicwise Daily Practice Problems (DPP) Physical Chemistry Part 1 JEE Main & Advanced>Chapter 5 - Thermodynamics>DPP 5.6>Q 3

Calculate

ΔU

and

ΔH

in calories if one mole of monoatomic ideal gas is heated at constant pressure of

1 atm

from

25 ° C

50 ° C

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Chapterwise/Topicwise Daily Practice Problems (DPP) Physical Chemistry Part 1 JEE Main & Advanced>Chapter 5 - Thermodynamics>DPP 5.6>Q 4

3.5 g

of a fuel (with molecular weight

28 g

), was burnt in a calorimeter which raised the temperature of

1 g

water from

25 ° C

67.3 ° C

. If all the heat generated was used in heating water, calculate heat of combustion of fuel.

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Chapterwise/Topicwise Daily Practice Problems (DPP) Physical Chemistry Part 1 JEE Main & Advanced>Chapter 5 - Thermodynamics>DPP 5.6>Q 5

A solution of

200 mL

1 M KOH

is added to

200 mL

1 M HCl

and the mixture after attaining reaction equilibrium shows a rise in temperature by

{ΔT}_{1}

. The experiment is repeated by using

50 mL

1 M KOH

and

50 mL 1 M HCl

which at equilibrium shows a rise in temperature by

{ΔT}_{2}

. Thus:

In which of the following process does entropy increase?

Important Questions on Thermodynamics

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