Thermodynamics Part-2 - Live session and RevisionContact Number: 9667591930 / 8527521718

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A 10 g piece of iron (C = 0.45 J/g°C) at 100 °C is dropped into 25 g of water (C = 4.2 J/g°C) at 27°C. Find the temperature of the iron and water system at thermal equilibrium.

1. 30 °C

2. 33 °C

3. 40 °C

4. None of these

2 mole of zinc is dissolved at HCI at $25\xb0\mathrm{C}$.

The work done in open vessel is:

1. -2.477 KJ

2. -4.955 KJ

3. 0.0489 KJ

4. None

A sample of an ideal gas is expanded 1 ${\mathrm{m}}^{3}$ to 3 ${\mathrm{m}}^{3}$ in a reversible process for which P = K${\mathrm{V}}^{2}$, with K = 6 bar/m. Work done by the gas is

1. 5200 kJ

2. 15600 kJ

3. 52 kJ

4. 5267.6 kJ

An ideal gas is taken around the cycle ABCA as shown in P-V diagram. The network done during the cycle is equal to :

1. 12 ${\mathrm{P}}_{1}{\mathrm{V}}_{1}$

2. 6 ${\mathrm{P}}_{1}{\mathrm{V}}_{1}$

3. 5 ${\mathrm{P}}_{1}{\mathrm{V}}_{1}$

4. ${\mathrm{P}}_{1}{\mathrm{V}}_{1}$

A gas expands against a variable pressure given by P = 20/V (where P in atm and V in L). During expansion from the volume of 1 liter to 10 liters, the gas undergoes a change in internal energy of 400 J. How much heat is absorbed by the gas during expansion?

1. 46 J

2. 4660 J

3. 5065.8 J

4. 4260 J

5 mole of an ideal gas expand isothermally and irreversibly from a pressure of 10 atm to 1 atm against a constant external pressure of 1 atm, ${\mathrm{W}}_{\mathrm{irr}}$ at 300 K is:

1. -15.921 KJ

2. -11.224 KJ

3. -110.83 KL

4. None of these

One mole of a non-ideal gas undergoes a change of state from (1.0 atm, 3.0 L, 200 K) to (4.0 atm, 5.0 L, 250 K) with a change in internal energy ($\u2206$U) = 40 L-atm. The change in enthalpy of the process in L-atm:

1. 43

2. 57

3. 42

4. None of these

Consider the reaction at 300 K ${\mathrm{C}}_{6}{\mathrm{H}}_{6}\left(\mathrm{l}\right)+\frac{15}{2}{\mathrm{O}}_{2}\left(\mathrm{g}\right)\to 6{\mathrm{CO}}_{2}\left(\mathrm{g}\right)+3{\mathrm{H}}_{2}\mathrm{O}\left(\mathrm{I}\right);(\u2206\mathrm{H})=-3271\mathrm{kJ}$. What is AU for the combustion of 1.5 moles of benzene at 27°C

1. -3267.25 kJ

2. -4900.88 kJ

3. -4906.5 kJ

4. -3274.75 kJ

When two moles of an ideal gas (${\mathrm{C}}_{\mathrm{P},\mathrm{m}}$ = $\frac{5}{2}$R) heated from 300 K to 600 K at constant pressure. The change in entropy of gas $\u2206$S is

1. $\frac{3}{2}\mathrm{R}\mathrm{In}2$

2. - $\frac{3}{2}\mathrm{R}\mathrm{In}2$

3. $5\mathrm{R}\mathrm{In}2$

4. $\frac{5}{2}\mathrm{R}\mathrm{In}2$

When one mole of an ideal gas is compressed to half of its initial volume and simultaneously heated to twice its initial temperature, the change in entropy of gas ($\u2206$S) is :

1. ${\mathrm{C}}_{\mathrm{P},\mathrm{m}}$ In 2

2. ${\mathrm{C}}_{\mathrm{v},\mathrm{m}}$ In 2

3. R In 2

4. (${\mathrm{C}}_{\mathrm{v},\mathrm{m}}$ = R) In 2

What is the change in entropy when 2.5 moles of water is heated from 27 °C to 87°C? Assume that the capacity is constant (${\mathrm{C}}_{\mathrm{P},\mathrm{m}}\left({\mathrm{H}}_{2}\mathrm{O}\right)=4.2\mathrm{J}/\mathrm{g}-\mathrm{k}\mathrm{in}\left(1.2\right)=0.18$)

1. 16.6 J/K

2. 9 J/K

3. 34.02 J/K

4. 1.89 J/K

At 25 °C, $\u2206\mathrm{G}\xb0$ for the process ${\mathrm{H}}_{2}\mathrm{O}$(l) $\rightleftharpoons $ ${\mathrm{H}}_{2}\mathrm{O}$(g) is 8.6 kJ. The vapor pressure of water at this temperature is near:

1. 24 torr

2. 285 torr

3. 32.17 torr

4. 100 torr

The standard enthalpy of formation of gaseous ${\mathrm{H}}_{2}\mathrm{O}$ at 298 K is -241.82 kJ/mol. Calculate $\u2206\mathrm{H}\xb0$ at 373 K given the following values of the molar heat capacities at constant pressure:

${\mathrm{H}}_{2}\mathrm{O}\left(\mathrm{g}\right)=33.58{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-4}$; ${\mathrm{H}}_{2}\left(\mathrm{g}\right)=29.84{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}$; ${\mathrm{O}}_{2}\left(\mathrm{g}\right)=29.37{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}$.

Assume that the heat capacities are independent of temperature :

1. -242.6 kJ/mol

2. -485.2 kJ/mol

3. -121.3 kJ/mol

4. -286.4 kJ/mol

Gasoline has an enthalpy of combustion 24000 kJ/gallon. When gasoline burns in an automobile engine, approximately 30% of the energy released is used to produce mechanical work. The remainder is lost as heat transfer to the engine's cooling system. As a start on estimating how much heat transfer is required, calculate what mass of water could be heated from 25 °C to 75 °C by the combustion of 1.0 gallons of gasoline in an automobile? (Given : C(${\mathrm{H}}_{2}\mathrm{O}$) = 4.18 J/g°C)

1. 34.45 kg

2. 80.383 kg

3. 22 kg

4. 224 kg

A 0.05 L sample of 0.2 M aqueous hydrochloric acid is added to 0.05 L of 0.2 M aqueous ammonia in a calorimeter. The heat capacity of the entire calorimeter system is 480 J/K. The temperature increase is 1.09 K. Calculate $\u2206\mathrm{rH}\xb0$ in kJ/mol for the following reaction:

$\mathrm{HCl}(\mathrm{aq}.)+{\mathrm{NH}}_{3}\left(\mathrm{aq}\right)\to {\mathrm{NH}}_{4}\mathrm{Cl}(\mathrm{aq}.)$

1. -52.32

2. -61.1

3. -55.8

4. -58.2

Boron can undergo the following reactions with the given enthalpy changes: 2B(s)

$2\mathrm{B}\left(\mathrm{s}\right)+\frac{3}{2}{\mathrm{O}}_{2}\to {\mathrm{B}}_{2}{\mathrm{O}}_{2}\left(\mathrm{s}\right);\u2206\mathrm{H}=-1260\mathrm{kJ}\phantom{\rule{0ex}{0ex}}2\mathrm{B}\left(\mathrm{s}\right)+3{\mathrm{H}}_{2}\to {\mathrm{B}}_{2}{\mathrm{H}}_{6}\left(\mathrm{s}\right);\u2206\mathrm{H}=30\mathrm{kJ}$

Assume no other reactions are occurring. If in a container (operating at constant pressure) which is isolated from the surrounding, a mixture of H2(gas) and ${\mathrm{O}}_{2}$ (gas) is passed over excess of B(s), then calculate the molar ratio (${\mathrm{O}}_{2};{\mathrm{H}}_{2}$) so that the temperature of the container does not change :

1. 15:3

2. 42:1

3. 1:42

4. 1:84

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