It is required to raise the temperature of water of a swimming pool from 20 ° C to 25 ° C . The pool holds 10 5 L of water. How much energy in joules will be required? Given that the specific heat of water is 4 . 184 J K - 1 g - 1 .

Given, T 1 = 20 ℃ . T 2 = 25 ℃ . V = 105 L . Q = ? ; C = 4 . 184 J K - 1 g - 1 . Mass of water = volume × density. = ( 10 5 × 10 3 ) mL × 1 g mL - 1 . = 10 8 g . Formula used, Q = m × c × ∆ T . = 10 8 × 4 . 184 × ( T 2 - T 1 ) . = 10 8 × 4 . 184 × ( 25 - 20 ) . = 10 8 × 4 . 184 × 5 . = 20 . 92 × 10 8 = 2 . 092 × 10 9 J .

A 1 . 250 g sample of octane C 8 H 18 is burnt in excess of oxygen in a bomb calorimeter. The temperature of the calorimeter rises from 294 . 05 K to 300 . 78 K . If heat capacity of the calorimeter is 8 . 93 kJ K - 1 , find heat transferred to the calorimeter. Also calculate the enthalpy combustion of the sample of octane.

Given, Weight of C 8 H 18 = 1 . 250 g . T 1 = 294 .05 K . T 2 = 300 .78 K . Heat Capacity = 8 . 93 kJ K - 1 . Heat transferred = ? Enthalpy = ? Formula used, H = Heat capacity × ∆ T . = 8 . 93 × T 2 - T 1 = 8 . 93 × ( 300 . 78 - 294 . 05 ) = 8 . 93 × 6 . 73 = 60 . 1 kJ . Enthalpy of Combustion = = heat transfered wt . of octane × molar mass of C 8 H 18 = 60.1 1.250 × 8 × 12 + 18 × 1 = 60 . 1 1 . 250 × 114 = 5481 . 1 kJ mol - 1 .

HARD

11th CBSE

IMPORTANT

Earn 100

The heat of Combustion of naphthalene $(C_{10} H_{8} (s))$ at constant volume was found to be $- 5133 kJ {mol}^{- 1}$ . Calculate the value of enthalpy change.

Important Questions on Thermodynamics

HARD

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>PROBLEMS FOR PRACTICE>Q 7

The molar heat of formation of

{NH}_{4} {NO}_{2} (s)

- 367.54 kJ

and those of

N_{2} O (g)

and

H_{2} O (l)

are

+ 81.46 kJ

and

- 285.78 kJ

respectively at

25 ° C

and

1.0

atmospheric pressure. Calculate the

ΔH

and

ΔU

for the reaction.

HARD

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>PROBLEMS FOR PRACTICE>Q 8

Determine the value of $ΔH$ and $ΔU$ for the reversible isothermal evaporation of $90.0 g$ of water at $100 ° C$ . Assume that water vapour behave as an ideal gas and heat of evaporation of water is $500$ $Cal g^{- 1}$ $(R = 2.0 Cal {mol}^{- 1} K^{- 1})$ .

HARD

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>PROBLEMS FOR PRACTICE>Q 1

It is required to raise the temperature of water of a swimming pool from

20 ° C

25 ° C

. The pool holds

10^{5} L

of water. How much energy in joules will be required? Given that the specific heat of water is

4.184 J K^{- 1} g^{- 1}

HARD

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>PROBLEMS FOR PRACTICE>Q 2

Specific heat of an elementary gas is found to be

0.313 J

at constant volume. If the molar mass of the gas is

40 g {mol}^{- 1}

, what is the atomicity of the gas?

HARD

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>PROBLEMS FOR PRACTICE>Q 1

1.250 g

sample of octane

(C_{8} H_{18})

is burnt in excess of oxygen in a bomb calorimeter. The temperature of the calorimeter rises from

294.05 K

300.78 K

. If heat capacity of the calorimeter is

8.93 kJ K^{- 1}

, find heat transferred to the calorimeter. Also calculate the enthalpy combustion of the sample of octane.

HARD

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>PROBLEMS FOR PRACTICE>Q 2

When

20.0 g

of ammonium nitrate

({NH}_{4} {NO}_{3})

is dissolved in

125 g

of water in a coffee-cup calorimeter, the temperature falls from

296.5 K

286.4 K

. Find the value of

q

for the Calorimeter.

EASY

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>PROBLEMS FOR PRACTICE>Q 3

0.16 g

of methane was subjected to combustion at

27 ° C

in a bomb calorimeter system. The temperature of the calorimeter system (including water) was found to rise by

0.5 ° C

. Calculate the heat of combustion of methane at (i) constant volume, and (ii) constant pressure. The thermal capacity of the calorimeter system is

17.7 kJ K^{- 1} (R = 8.314 kJ K^{- 1} {mol}^{- 1})

EASY

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 7 - Thermodynamics>PROBLEMS FOR PRACTICE>Q 1

Ethylene on combustion gives carbon dioxide and water. Its enthalpy of combustion is

141.0 kJ {mol}^{- 1}

. If the enthalpy of formation of

{CO}_{2}

and

H_{2} O

are

393.3 kJ

and

286.2 kJ

respectively. Calculate the enthalpy of formation of ethylene.

The heat of Combustion of naphthalene C10H8s at constant volume was found to be –5133 kJ mol-1. Calculate the value of enthalpy change.

Important Questions on Thermodynamics

Learn and Prepare for any exam you want !

The heat of Combustion of naphthalene $(C_{10} H_{8} (s))$ at constant volume was found to be $- 5133 kJ {mol}^{- 1}$ . Calculate the value of enthalpy change.