Heat Capacity...

Heat Capacity at Constant Volume

Trending Questions

Q. Two moles of an ideal gas is heated at constant pressure of one atmosphere from

27^{o} C t o 127^{o} C .

C_{v, m} = 20 + 10^{- 2} T J K^{- 1} m o l^{- 1},

then

q

and

△ U

for the process are respectively:

6362.8 J, 4700 J
3037.2 J, 4700 J
3181.4 J, 2350 J
7062.8, 5400 J

View Solution

Q. At constant volume, the specific heat of a gas is 0.075

c a l K^{- 1} g^{- 1}

and its molecular weight is 40

g m o l^{- 1}

. The atomicity of the gas is:
Given: R = 2 cal

K^{- 1} m o l^{- 1}

Monoatomic
Diatomic
Triatomic
None of the above

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Q. The standard free energy change

(Δ G^{\circ})

for 50% dissociation of

N_{2} O_{4}

into

N O_{2}

27^{\circ} C

and 1 atm pressure is

- x J m o l^{- 1}

. The value of

x

is (Nearest Integer)

[Given : R = 8.31 J K^{- 1} m o l^{- 1}, l o g (1.33) = 0.1239, l n (10) = 2.3]

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Q. What is the value of the change in internal energy at 1 atm in the following process?

H_{2} O (l, 323 K) \to H_{2} O (g, 423 K)

Given :

C_{v, m} (H_{2} O, 1) = 75.0 J K^{- 1}; C_{p, m} (H_{2} O, g) = 33.314 J K^{- 1} m o l^{- 1}; Δ H_{v a p} at 373 K = 40.7 k J / m o l

$42.910 kJ/mol$
$43.086 kJ/mol$
$42.600 kJ/mol$
$49.600 kJ/mol$

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Q. Temperature of one mole of helium gas is increased by

4^{\circ}

. Thus, increase in internal energy is

6 cal
12 cal
3 cal
24 cal

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Q. If

C_{v} = 4.96 c a l / m o l . K

then increase in internal energy when temperature of 2 moles of this gas is increased from

340 K

342 K

$19.84 c a l$
$27.80 c a l$
$13.90 c a l$
$9.92 c a l$

View Solution

Q. Choose the correct option related to the specific heat at constant volume

C_{v}

All of these
$C_{v} = \frac{R}{γ - 1}$
$C_{v} = \frac{R}{γ}$
$C_{v} = \frac{1}{2} γ R$

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Q. For a gas

(R / C_{v}) = 0.67

the gas is made up of molecules which are
(

R

= gas constant and

C_{v}

= heat capacity at constant volume)

monoatomic
diatomic
polyatomic
mixture of gases

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In adiabatic irreversible expansion of an ideal gas against a constant external pressure $P_{2},$ the P - V work is given by ?

$- W_{i r r} = n R (T_{2} - \frac{T_{1} P_{2}}{P_{1}})$
$- W_{i r r} = n R (T_{2} + \frac{T_{1} P_{2}}{P_{1}})$
$- W_{i r r} = n R T_{1} (1 - \frac{P_{2}}{P_{1}})$
$- W_{i r r} = n R T_{2} (1 - \frac{P_{2}}{P_{1}})$

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Q. A thermally insulated vessel is divided into two compartments A and B by a partition of insulating material. Compartment A has 0.1 mole of Helium at

427^{\circ} C

and 1 atm and compartment B has

x

mol of Neon at

127^{\circ} C

and 1 atm. If partition is removed and final temperature of gas is

227^{\circ} C

, then the value of

10 x

is . [Assume

C_{v} = \frac{3 R}{2}

for both gases ]

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Q. A heat engine carries 1 mole of an ideal monoatomic gas around the cycle as shown in the figure, the amount of heat added in the process AB and heat removed in th process CA are:

$q_{A B} = 450 R$ and $q_{C A} = - 225$ R
$q_{A B} = 450 R$ and $q_{C A} = - 450$ R
$q_{A B} = 375 R$ and $q_{C A} = - 450$ R
$q_{A B} = 450 R$ and $q_{C A} = - 375$ R

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Q. What is the final temperature of

0.10

mole monoatomic ideal gas that performs

75 cal

of work adiabatically if the initial temperature is

227^{\circ} C ?

(use

R = 2 {cal K}^{- 1} {mol}^{- 1}

)

$250 K$
$300 K$
$350 K$
$750 K$

View Solution

In adiabatic irreversible expansion of an ideal gas against a constant external pressure $P_{2},$ the P - V work is given by ?

$- W_{i r r} = n R (T_{2} - \frac{T_{1} P_{2}}{P_{1}})$
$- W_{i r r} = n R (T_{2} + \frac{T_{1} P_{2}}{P_{1}})$
$- W_{i r r} = n R T_{1} (1 - \frac{P_{2}}{P_{1}})$
$- W_{i r r} = n R T_{2} (1 - \frac{P_{2}}{P_{1}})$

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Q. If K=1.19×10-4 at 623K. Find 🔼G

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Q. For the reaction,

2 N O (g) + O_{2} (g) \to 2 N O_{2} (g)

the value of

Δ H

- 113.1 kJ

. If

6.0 moles

N O

reacts with

3.0 moles

O_{2}

1.0 atm

and

300 K

to form

N O_{2}

. Calculate the work done against a pressure of

1.0 atm

.
(Take

R = \frac{1}{12} {L atm mol}^{- 1} K^{- 1}

)

$7.56 kJ$
$- 75 J$
$- 7.56 kJ$
$75 J$

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Q. A solution containing 28 g phosphorous in 315 g

C S_{2}

(b.pt.

{46.3}^{o} C

) boils at

{47.98}^{o} C, K_{b}

for

C S_{2}

is 2.34 K

m o l^{- 1} k g

. Its molecular formula is

P_{x}

. Find

x

. Assume its complete association.

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Q. For reaction,

2 N O {C l}_{(g)} ⇌ 2 {N O}_{(g)} + {C l}_{2 (g)}; K_{c}

427^{o} C

3 \times 10^{- 6} L {m o l}^{- 1}

. The value of

K_{p}

is nearly:

$7.50 \times 10^{- 5}$
$2.50 \times 10^{- 5}$
$2.50 \times 10^{- 4}$
$1.75 \times 10^{- 4}$

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Q. When

10 g

A l

is used for reduction in each of the following alumino thermic reactions, which reaction would generate more heat and by how much ?
a.

2 A l + C r_{2} O_{3} \to A l_{2} O_{3} + 2 C r

2 A l + F e_{2} O_{3} \to A l_{2} O_{3} + 2 F e

Standard heat of formation of

A l_{2} O_{3}

C r_{2} O_{3}

and

F e_{2} O_{3}

are

- 1676 k J

- 1141 k J

and

- 822.2 k J

, respectively.

Reaction (b) produces more heat by $59.04 k J$
Reaction (a) produces more heat by $59.04 k J$
Reaction(a) and (b) produces equal heat
None of these

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Q. A 4:1 molar mixture of

H e

and

C H_{4}

is contained in a vessel at 20

b a r

pressure. Due to a hole in the vessel, the gas mixture leaks out. What is the composition ratio of the mixture effusing out initially?

$\frac{r_{H e}}{r_{C H_{4}}} = 1 : 4$ .
$\frac{r_{H e}}{r_{C H_{4}}} = 8 : 1$ .
$\frac{r_{H e}}{r_{C H_{4}}} = 1 : 8$ .
None of these

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Δ G^{o}

for the reaction:

A g C l (s) + 1 / 2 H_{2} (g) ⟶ A g (s) + H^{+} + C l^{-}

- 21.52 k J

Δ G^{o}

for the reaction:

2 A g C l (s) + H_{2} (g) \to 2 A g (s) + 2 H^{+} + 2 C l^{-}

is:

$- 21.52 K J$
$- 10.76 K J$
$- 45.04 K J$
$- 43.04 K J$

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Q. Reaction of methanol with dioxygen was carried out and

Δ U

was found to be

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

298 K

. The enthalpy change for the reaction will be

C H_{3} O H_{(l)} + \frac{3}{2} O_{2 (g)} \to C O_{2 (g)} + 2 H_{2} O_{(l)}

;

Δ U = - 726 k J m o l^{- 1}

$- 727 k J m o l^{- 1}$
$+ 741. 5 k J m o l^{- 1}$
$+ 727.2 k J m o l^{- 1}$
$- 741.5 k J m o l^{- 1}$

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Q. A new flurocarbon of molar mass

102 g m o l^{1}

was placed in an electrically heated vessel. When the pressure was 650 torr, the liquid boiled at

77^{\circ} C

. After the boiling point had been reached, it was found that a current of 0.25 A from a 12.0 volt supply passed for 600 sec vaporises 1.8 g of the sample. The molar enthalpy & internal energy of vaporisation of new flourocarbon will be :

$Δ H = 102 k J / m o l, Δ E = 99.1 k J / m o l$
$Δ H = 95 k J / m o l, Δ E = 100.3 k J / m o l$
$Δ H = 107 k J / m o l, Δ E = 105.1 k J / m o l$
$Δ H = 92.7 k J / m o l, Δ E = 97.4 k J / m o l$

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Q. One kilogram water at

0^{o} C

is brought into contact with a heat reservoir at

100^{o} C

. Find:
(a) Change in entropy when temperature reaches to

100^{o} C

.
(b) What is the change in entropy of reservoir?
(c) Change in entropy universe.
(d) The nature of process.

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Q. For the reaction

A g^{+} (a q) + C l^{-} (a q) ⇌ A g C l (s)

; the

Δ G^{o}

values for

A g^{+} (a q), C l^{-} (a q)

and

A g C l (s)

are + 77, -129 and -109 kJ mol

^{- 1}

. Write the cell representation of above reaction and calculate

K_{s p}

of AgCl at 298 K.
(Multiply the ans by

10^{10}

)

View Solution

Q. Two moles of an ideal gas is heated at constant pressure of one atmosphere from

27^{o} C t o 127^{o} C .

C_{v, m} = 20 + 10^{- 2} T J K^{- 1} m o l^{- 1},

then

q

and

△ U

for the process are respectively:

6362.8 J, 4700 J
3037.2 J, 4700 J
7062.8, 5400 J
3181.4 J, 2350 J

View Solution

C H_{3} - O | | C - C H_{3} (g) ⇌ C H_{3} - C H_{3} (g) + C O (g)

The initial pressure of

{C H}_{3} C O {C H}_{3}

100 m m o f H g

. When equilibrium is achieved, the mole fraction of

C O (g)

1 / 3

hence,

K_{p}

is:

$100 m m$
$50 m m$
$25 m m$
$150 m m$

View Solution

Q. If,

K_{p} = K_{c} \times {[R T]}^{Δ n}

, for the reaction ;

2 C O_{2} (g) + 2 C a C O_{3} (s) ⇌ 2 C a C_{2} (s) + 5 O_{2} (g)

;

Δ n

is equal to :

View Solution

Q. If

C_{v} = 4.96 c a l / m o l . K

then increase in internal energy when temperature of 2 moles of this gas is increased from

340 K

342 K

$27.80 c a l$
$19.84 c a l$
$13.90 c a l$
$9.92 c a l$

View Solution

Q. The molar heat capacity of oxygen gas is given by the expression

C_{v} = a + b T + c T^{2}

where

a, b

and

c

are constants. What will be the change in the internal energy of

8 g

of oxygen, if it is heated from

200 K

300 K

at constant volume? Assume oxygen to be an ideal gas. (Given,

a = 1.2 {JK}^{- 1} {mol}^{- 1}

b = 12.8 \times 10^{- 2} {JK}^{- 2} {mol}^{- 1}

c = 1.0 \times 10^{- 7} {JK}^{- 3} {mol}^{- 1}

$850.60 J$
$950.50 J$
$830.16 J$
$853.62 J$

View Solution

Δ G^{o}

of the cell reaction

A g C l (s) + 1 / 2 H_{2} (g) \to A g (s) + H^{+} (a q .) + {C l}^{-} (a q)

- 21.52 k J

Calculate the EMF for the cell reaction:

2 A g C l (c) + H_{2} (g) \to A g (s) + 2 H^{+} (a q .) + 2 {C l}^{-} (a q .)

$0.223 V$
$0.112 V$
$0.446 V$
$0.337 V$

View Solution