A piston filled with 0.04 mol of an ideal gas expands reversibly from 50.0 mL to 375 mL at a constant temperature of 3 7 . 0 ∘ C . As it does so, it absorbs 208 J of heat. The values of q and w for the process will be (R = 8.314 J/mol K) (ln7.5 = 2.01)

q = + 2 0 8 J , w ⁡ = - 2 0 8 J

q = + 2 0 8 J , w ⁡ = + 2 0 8 J

q = - 2 0 8 J , w ⁡ = - 2 0 8 J

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The Joule Thomson coefficient for an ideal gas is equal to (positive/zero/negative).

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Important Questions on Chemical Thermodynamics

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

During compression of a spring the work done is

10 k J

and

2 k J

escaped to the surroundings as heat. The change in internal energy,

Δ U (i n k J)

is:

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

For a reaction,

A (g) \to A (l); ΔH = - 3 RT .

The correct statement for the reaction is

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

Following figure shows two processes

A

and

B

for a gas. If

∆ Q_{A}

and

∆ Q_{B}

are the amount of heat absorbed by the system in two cases, and

∆ U_{A}

and

∆ U_{B}

are changes in internal energies, respectively, then:
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MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

Identify the equation in which change in enthalpy is equal to change in internal energy

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

Δ U

is equal to:

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

For the reaction:

X_{2} {O_{4}}_{(l)} \to 2 X {O_{2}}_{(g)}

∆ U = 2 .1 kcal, ∆ S = 20 cal K^{- 1}

300 K

Hence,

∆ G

is:

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

For complete combustion of ethanol,

C_{2} H_{5} OH (l) + 3 O_{2} (g) \to 2 {CO}_{2} (g) + 3 H_{2} O (l)

,
the amount of heat produced as measured in bomb calorimeter, is

{1364.47 kJ mol}^{-1}

25 ℃

. Assuming ideality the Enthalpy of combustion,

Δ_{c} H

, for the reaction will be:

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

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

The heat of reaction for

$C_{10} H_{8} (s) + 12 O_{2} (g) ⟶ 10 {CO}_{2} (g) + 4 H_{2} O (l)$ at constant volume is $- 1228.2 kcal$ at $25^{0} C$ . The heat of reaction at constant pressure and same temperature is

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

The first law of thermodynamics for isothermal process is

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

Which of the following process best describes atomization of

C H_{4} (g) ?

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

Two moles on an ideal gas is expanded isothermally and reversibly at 300 K form 1 L to 10 L. The enthalpy change in KJ is

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

A piston filled with 0.04 mol of an ideal gas expands reversibly from 50.0 mL to 375 mL at a constant temperature of

37 . 0^{\circ} C

. As it does so, it absorbs 208 J of heat. The values of q and w for the process will be
(R = 8.314 J/mol K) (ln7.5 = 2.01)

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

Tin is obtained from cassiterite by reduction with coke. Use the data given below to determine the minimum temperature (in $K$ ) at which the reduction of cassiterite by coke would take place.

$298 K : Δ_{f} H^{0} ({SnO}_{2} (s)) = - 581.0 kJ {mol}^{- 1}, Δ_{f} H^{0} ({CO}_{2} (g)) = - 394.0 kJ {mol}^{- 1}$

$S^{0} ({SnO}_{2} (s)) = 56.0 {JK}^{- 1} {mol}^{- 1}, S^{0} (Sn (s)) = 52.0 {JK}^{- 1} {mol}^{- 1}$

$S^{0} (C (s)) = 6.0 {JK}^{- 1} {mol}^{- 1}, S^{0} ({CO}_{2} (g)) = 210.0 {JK}^{- 1} {mol}^{- 1}$

Assume that the enthalpies and the entropies are temperature independent.

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

The difference between

∆ H

and

∆ U

(∆ H - ∆ U)

, when the combustion of one mole of heptane

(l)

is carried out at a temperature

T

, is equal to:

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

For the reaction

$N_{2} O_{4} (g) ⟶ 2 {NO}_{2} (g)$

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

2

moles of a monoatomic ideal gas at

25^{o} C

is heated reversibly at a constant pressure of

2 atm

to reach a final temperature of

125^{o} C

. Calculate the

Δ H . (C_{v} = \frac{3}{2} R)

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

For which of the following systems, the difference between $ΔH$ and $ΔU$ is not significant?

(i) Solids

(ii) Gases

(iii) Mixture of gases and liquids

(iv) Liquids

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

A gas undergoes change from state

A

to state

B

. In this process, the heat absorbed and work done by the gas is

5 J and 8 J

, respectively. Now gas is brought back to

A

by another process during which

3 J

of heat is evolved. In this reverse process of

B to A

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

Given:

C (graphite) + O_{2} (g) \to {CO}_{2} (g); Δ_{r} H^{o} = - 393 .5 kJ {mol}^{- 1}

H_{2} (g) + \frac{1}{2} O_{2} (g) \to H_{2} O (l); Δ_{r} H^{o} = - 285 .8 kJ {mol}^{- 1}

{CO}_{2} (g) + 2 H_{2} O (l) \to {CH}_{4} (g) + 2 O_{2} (g); Δ_{r} H^{o} = + 890 .3 kJ {mol}^{- 1}

Based on the above thermochemical equations, the value of

Δ_{r} H^{o}

298 K

for the reaction

C (graphite) + 2 H_{2} (g) \to {CH}_{4} (g)

will be:

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics>First Law of Thermodynamics

The above

P - V

diagram represents the thermodynamic cycle of an engine, operating with an ideal mono-atomic gas. The amount of heat, extracted from the source in a single cycle, is:

The Joule Thomson coefficient for an ideal gas is equal to (positive/zero/negative).

Important Questions on Chemical Thermodynamics

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