NCERT Solutions-Thermodynamics for Class 11 Chemistry Chapter 6

NCERT Solutions for Class 11 Chemistry Chapter 6 Thermodynamics


Q-1: Choose the correct answer. A thermodynamic state function is a quantity

(i) used to determine heat changes
(ii) whose value is independent of the path
(iii) used to determine pressure-volume work
(iv) whose value depends on temperature only

Ans:

(ii) whose value is independent of the path.

Reason:

Functions like pressure, volume and temperature depend on the state of the system only and not on the path.

Q-2: For the process to occur under adiabatic conditions, the correct condition is:
(i) ∆T = 0   (ii) ∆p = 0
(iii) q = 0   (iv) w = 0

Ans:

(iii) q = 0

Reason:

For an adiabatic process, heat transfer is zero, i.e., q = 0.

Q-3: The enthalpies of all elements in their standard states are:

(i) Unity   (ii) Zero

(iii) < 0     (iv) Different for every element

Ans:

(ii) Zero

Q-4: ∆U0 of combustion of methane is – X kJ mol–1. The value of ∆H0 is

(i) =

\(\begin{array}{l}\Delta U^{\Theta }\end{array} \)

(ii) >

\(\begin{array}{l}\Delta U^{\Theta }\end{array} \)

(iii) <

\(\begin{array}{l}\Delta U^{\Theta }\end{array} \)

(iv) 0

Ans:

(iii) <

\(\begin{array}{l}\Delta U^{\Theta }\end{array} \)

Reason:

\(\begin{array}{l}\Delta H^{\Theta } = \Delta U^{\Theta } + \Delta n_{g}RT\end{array} \)

;

\(\begin{array}{l}\Delta U^{\Theta }\end{array} \)

= – Y

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

,

\(\begin{array}{l}\Delta H^{\Theta } = ( – Y) + \Delta n_{g}RT \Rightarrow \Delta H^{\Theta } < \Delta U^{\Theta }\end{array} \)

Q-5: The enthalpy of combustion of methane, graphite and dihydrogen at 298 K are –890.3 kJ mol–1 –393.5 kJ mol–1, and –285.8 kJ mol–1, respectively. Enthalpy of the formation of CH4 (g) will be

(i) -74.8 kJ

\(\begin{array}{l}mol^{-1}\end{array} \)

(ii) -52.27 kJ

\(\begin{array}{l}mol^{-1}\end{array} \)

(iii) +74.8 kJ

\(\begin{array}{l}mol^{-1}\end{array} \)

(iv) +52 kJ

\(\begin{array}{l}mol^{-1}\end{array} \)

Ans:

(i) -74.8 kJ

\(\begin{array}{l}mol^{-1}\end{array} \)

1. CH4(g)  + 2O2(g)

\(\begin{array}{l}\rightarrow\end{array} \)

CO2(g) + 2H2O(g)

\(\begin{array}{l}\Delta H = -890.3kJmol^{-1}\end{array} \)

2. C(s) + O2(g)  

\(\begin{array}{l}\rightarrow\end{array} \)

CO2(g)

\(\begin{array}{l}\Delta H = -393.5kJmol^{-1}\end{array} \)

3. 2H2(g) + O2(g)

\(\begin{array}{l}\rightarrow\end{array} \)

2H2O(g)

\(\begin{array}{l}\Delta H = -285.8kJmol^{-1}\end{array} \)

C(s) + 2H2(g)

\(\begin{array}{l}\rightarrow\end{array} \)

CH4(g)

\(\begin{array}{l}\Delta _{f}H_{CH_{4}}\end{array} \)

  =

\(\begin{array}{l}\Delta _{c}H_{c}\end{array} \)

+

\(\begin{array}{l}2\Delta _{f}H_{H_{2}}\end{array} \)

\(\begin{array}{l}\Delta _{f}H_{CO_{2}}\end{array} \)

= [ -393.5 +2(-285.8) – (-890.3)] kJ

\(\begin{array}{l}mol^{-1}\end{array} \)

= -74.8 kJ

\(\begin{array}{l}mol^{-1}\end{array} \)

Q-6: A reaction, A + B → C + D + q, is found to have a positive entropy change. The reaction will be

(i) possible at high temperature

(ii) possible only at low temperature

(iii) not possible at any temperature

(iv) possible at any temperature

Ans:

(iv) possible at any temperature

\(\begin{array}{l}\Delta G\end{array} \)

should be –ve for spontaneous reaction to occur

\(\begin{array}{l}\Delta G\end{array} \)

=

\(\begin{array}{l}\Delta H\end{array} \)

– T

\(\begin{array}{l}\Delta S\end{array} \)

As per the given question,

\(\begin{array}{l}\Delta H\end{array} \)

is –ve ( as heat is evolved)

\(\begin{array}{l}\Delta S\end{array} \)

is +ve

Therefore,

\(\begin{array}{l}\Delta G\end{array} \)

is negative

So, the reaction will be possible at any temperature.

Q-7: In a process, 701 J of heat is absorbed by a system, and 394 J of work is done by the system. What is the change in internal energy for the process?

Ans:

As per Thermodynamics 1st law,

\(\begin{array}{l}\Delta U\end{array} \)

= q + W(i);

\(\begin{array}{l}\Delta U\end{array} \)

internal energy = heat

W = work done

W = -594 J (work done by the system)

q = +701 J (+ve as heat is absorbed)

Now,

\(\begin{array}{l}\Delta U\end{array} \)

= 701 + (-594)

\(\begin{array}{l}\Delta U\end{array} \)

= 307 J

Q-8: The reaction of cyanamide, NH2CN(s), with dioxygen was carried out in a bomb calorimeter, and ∆U was found to be –742.7 kJ mol–1 at 298 K. Calculate the enthalpy change for the reaction at 298 K.

NH2CN(g) + 3/2 O2(g) N2(g) + CO2(g) + H2O(l)

Ans:

\(\begin{array}{l}\Delta H\end{array} \)

is given by,

\(\begin{array}{l}\Delta H = \Delta U + \Delta n_{g}RT\end{array} \)

………………(1)

\(\begin{array}{l}\Delta n_{g}\end{array} \)

= change in number of moles

\(\begin{array}{l}\Delta U\end{array} \)

= change in internal energy

Here,

\(\begin{array}{l}\Delta n_{g} = \sum n_{g}(product) – \sum n_{g}(reactant)\end{array} \)

= (2 – 1.5) moles

\(\begin{array}{l}\Delta n_{g}\end{array} \)

= 0.5 moles

Here,

T =298 K

\(\begin{array}{l}\Delta U\end{array} \)

= -742.7

\(\begin{array}{l}kJmol^{-1}\end{array} \)

R  =

\(\begin{array}{l}8.314\times 10^{-3}kJmol^{-1}K^{-1}\end{array} \)

Now, from (1)

\(\begin{array}{l}\Delta H = (-742.7 kJmol^{-1}) + (0.5mol)(298K)( 8.314\times 10^{-3}kJmol^{-1}K^{-1})\end{array} \)

= -742.7 + 1.2

\(\begin{array}{l}\Delta H\end{array} \)

= -741.5

\(\begin{array}{l}kJmol^{-1}\end{array} \)

Q-9: Calculate the number of kJ of heat necessary to raise the temperature of 60.0 g of aluminium from 35°C to 55°C. The molar heat capacity of Al is 24 J mol–1 K–1.

Ans:

Expression of heat(q),

\(\begin{array}{l}q = mCP\Delta T\end{array} \)

;………………….(a)

\(\begin{array}{l}\Delta T\end{array} \)

= Change in temperature

c = molar heat capacity

m = mass of substance

From (a)

\(\begin{array}{l}q = ( \frac{60}{27}mol )(24mol^{-1}K^{-1})(20K)\end{array} \)

q = 1066.67 J = 1.067 KJ

Q-10: Calculate the enthalpy change on freezing of 1.0 mol of water at 10.0°C to the ice at –10.0°C. ∆fusH = 6.03 kJ mol–1 at 0°C.

\(\begin{array}{l}C_{p}[H_{2}O_{(l)}] = 75.3 J\;mol^{-1}K^{-1}\end{array} \)

\(\begin{array}{l}C_{p}[H_{2}O_{(s)}] = 36.8 J\;mol^{-1}K^{-1}\end{array} \)

Ans:

\(\begin{array}{l}\Delta H_{total}\end{array} \)

= sum of the changes given below:

(a) Energy change that occurs during the transformation of 1 mole of water from

\(\begin{array}{l}10^{\circ}C\;to\;0^{\circ}C\end{array} \)

.

(b) Energy change that occurs during the transformation of 1 mole of water at

\(\begin{array}{l}0^{\circ}C\end{array} \)

  to  1 mole of ice at

\(\begin{array}{l}0^{\circ}C\end{array} \)

.

(c) Energy change that occurs during the transformation of 1 mole of ice from

\(\begin{array}{l}0^{\circ}C\;to\;(-10)^{\circ}C\end{array} \)

.

\(\begin{array}{l}\Delta H_{total} = C_{p}[H_{2}OCl]\Delta T + \Delta H_{freezing} C_{p}[H_{2}O_{l}]\Delta T\end{array} \)

= (75.3

\(\begin{array}{l}J mol^{-1}K^{-1}\end{array} \)

)(0 – 10)K + (-6.03*1000

\(\begin{array}{l}J mol^{-1}\end{array} \)

(-10-0)K

= -753

\(\begin{array}{l}J mol^{-1}\end{array} \)

– 6030

\(\begin{array}{l}J mol^{-1}\end{array} \)

– 368

\(\begin{array}{l}J mol^{-1}\end{array} \)

= -7151

\(\begin{array}{l}J mol^{-1}\end{array} \)

= -7.151

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

Thus, the required change in enthalpy for the given transformation is -7.151

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

.

Q-11 Enthalpy of combustion of carbon to CO2 is –393.5 kJ mol–1. Calculate the heat released upon the formation of 35.2 g of CO2 from carbon and dioxygen gas.

Ans:

Formation of carbon dioxide from di-oxygen and carbon gas is given as:

C(s) + O2(g) → CO2(g);

\(\begin{array}{l}\Delta _{f}H\end{array} \)

= -393.5

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

1 mole CO2 = 44g

Heat released during formation of 44g CO2 = -393.5

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

Therefore, the heat released during the formation of 35.2g of CO2  can be calculated as

=

\(\begin{array}{l}\frac{-393.5kJmol^{-1}}{44g}\times 35.2g\end{array} \)

= -314.8

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

Q-12: Enthalpies of formation of CO (g), CO2 (g), N2(g) and N2O4 (g) are –110, – 393, 81 and 9.7 kJ mol–1, respectively. Find the value of ∆rH for the reaction:

N2O4(g) + 3CO(g) N2O(g) + 3 CO2(g)

Ans:

\(\begin{array}{l}\Delta _{r}H\end{array} \)

for any reaction is defined as the difference between

\(\begin{array}{l}\Delta _{f}H\end{array} \)

value of products and

\(\begin{array}{l}\Delta _{f}H\end{array} \)

value of reactants.”

\(\begin{array}{l}\Delta _{r}H = \sum \Delta _{f}H (products) – \sum \Delta _{f}H (reactants)\end{array} \)

Now, for

N2O4(g) + 3CO(g) à N2O(g) + 3 CO2(g)

\(\begin{array}{l}\Delta _{r}H = [(\Delta _{f}H(N_{2}O) + (3\Delta _{f}H(CO_{2})) – (\Delta _{f}H(N_{2}O_{4}) + 3\Delta _{f}H(CO))]\end{array} \)

Now, substituting the given values in the above equation, we get:

\(\begin{array}{l}\Delta _{r}H\end{array} \)

= [{81

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

+ 3(-393)

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

} – {9.7

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

+ 3(-110)

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

}]

\(\begin{array}{l}\Delta _{r}H\end{array} \)

= -777.7

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

Q-13: Given N2 (g) + 3H2 (g) → 2NH3 (g) ; ∆rH0= –92.4 kJ mol–1
What is the standard enthalpy of the formation of NH3 gas?

Ans:

“Standard enthalpy of formation of a compound is the enthalpy that takes place during the formation of 1 mole of a substance in its standard form, from its constituent elements in their standard state.”

Dividing the chemical equation given in the question by 2, we get

(0.5)N2(g) + (1.5)H2(g) → 2NH3(g)

Therefore, standard enthalpy for formation of ammonia gas

= (0.5)

\(\begin{array}{l}\Delta _{r}H^{\Theta }\end{array} \)

= (0.5)(-92.4

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

)

= -46.2

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

Q-14: Calculate the standard enthalpy of formation of CH3OH(l) from the following data:

CH3OH(l) + 3/2 O2(g) CO2(g) + 2H2O(l);

\(\begin{array}{l}\Delta _{r}H^{\Theta }\end{array} \)

= -726

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

C(g) + O2(g) CO2(g);

\(\begin{array}{l}\Delta _{c}H_{\Theta }\end{array} \)

= -393

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

H2(g) + 1/2 O2(g) H2O(l);

\(\begin{array}{l}\Delta _{f}H^{\Theta }\end{array} \)

= -286

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

Ans:

C(s) + 2H2O(g) + (1/2)O2(g) → CH3OH(l) …………………………(i)

CH3OH(l) can be obtained as follows,

\(\begin{array}{l}\Delta _{f}H_{\Theta }\end{array} \)

[CH3OH(l)] =

\(\begin{array}{l}\Delta _{c}H_{\Theta }\end{array} \)

2

\(\begin{array}{l}\Delta _{f}H_{\Theta }\end{array} \)

\(\begin{array}{l}\Delta _{r}H_{\Theta }\end{array} \)

= (-393

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

) +2(-286

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

) – (-726

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

)

= (-393 – 572 + 726)

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

= -239

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

Thus,

\(\begin{array}{l}\Delta _{f}H_{\Theta }\end{array} \)

[CH3OH(l)] = -239

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

Q-15: Calculate the enthalpy change for the process

CCl4(g) C(g) + 4Cl(g) and determine the value of bond enthalpy for C-Cl in CCl4(g).

\(\begin{array}{l}\Delta _{vap}H^{\Theta }\end{array} \)

(CCl4) = 30.5

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

.

\(\begin{array}{l}\Delta _{f}H^{\Theta }\end{array} \)

(CCl4) = -135.5

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

.

\(\begin{array}{l}\Delta _{a}H^{\Theta }\end{array} \)

(C) = 715

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

,

\(\begin{array}{l}\Delta _{a}H^{\Theta }\end{array} \)

  is a enthalpy of atomisation

\(\begin{array}{l}\Delta _{a}H^{\Theta }\end{array} \)

(Cl2) = 242

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

.

Ans:

“ The chemical equations implying the given values of enthalpies” are:

(1) CCl4(l) à CCl4(g) ;

\(\begin{array}{l}\Delta _{vap}H^{\Theta }\end{array} \)

= 30.5

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

(2) C(s) à C(g)

\(\begin{array}{l}\Delta _{a}H^{\Theta }\end{array} \)

= 715

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

(3) Cl2(g) à 2Cl(g) ;

\(\begin{array}{l}\Delta _{a}H^{\Theta }\end{array} \)

= 242

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

(4) C(g) + 4Cl(g) à CCl4(g);

\(\begin{array}{l}\Delta _{f}H^{\Theta }\end{array} \)

= -135.5

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

\(\begin{array}{l}\Delta H\end{array} \)

for the process CCl4(g) à C(g) + 4Cl(g) can be measured as:

\(\begin{array}{l}\Delta H = \Delta _{a}H^{\Theta }(C) + 2\Delta _{a}H^{\Theta }(Cl_{2}) – \Delta _{vap}H^{\Theta } – \Delta _{f}H\end{array} \)

= (715

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

) + 2(

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

) – (30.5

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

) – (-135.5

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

)

Therefore,

\(\begin{array}{l}H = 1304kJmol^{-1}\end{array} \)

The value of bond enthalpy for C-Cl in CCl4(g)

=

\(\begin{array}{l}\frac{1304}{4}kJmol^{-1}\end{array} \)

= 326

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

Q-16: For an isolated system, ∆U = 0, what will be ∆S?

Ans:

\(\begin{array}{l}\Delta U\end{array} \)

is positive ;

\(\begin{array}{l}\Delta U\end{array} \)

> 0.

As

\(\begin{array}{l}\Delta U\end{array} \)

= 0, then

\(\begin{array}{l}\Delta S\end{array} \)

will be +ve, and as a result, the reaction will be spontaneous.

Q-17: For the reaction at 298K,

2A + B  C

\(\begin{array}{l}\Delta H\end{array} \)

= 400

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

\(\begin{array}{l}\Delta H\end{array} \)

= 0.2

\(\begin{array}{l}kJ mol^{-1}K^{-1}\end{array} \)

At what temperature will the reaction become spontaneous considering

\(\begin{array}{l}\Delta S\end{array} \)

and

\(\begin{array}{l}\Delta H\end{array} \)

to be constant over the temperature range?

Ans:

Now,

\(\begin{array}{l}\Delta G = \Delta H – T\Delta S\end{array} \)

Let the given reaction is at equilibrium, then

\(\begin{array}{l}\Delta T\end{array} \)

will be:

T =

\(\begin{array}{l}(\Delta H – \Delta G)\frac{1}{\Delta S}\end{array} \)

\(\begin{array}{l}\frac{\Delta H}{\Delta S}\end{array} \)

; (

\(\begin{array}{l}\Delta G\end{array} \)

= 0 at equilibrium)

= 400

\(\begin{array}{l}kJ mol^{-1}\end{array} \)

/0.2

\(\begin{array}{l}kJ mol^{-1}K^{-1}\end{array} \)

Therefore, T = 2000K

Thus, for the spontaneous,

\(\begin{array}{l}\Delta G\end{array} \)

must be –ve and T > 2000K.

Q-18: For the reaction

2Cl(g) Cl2(g)

What are the signs of

\(\begin{array}{l}\Delta S\end{array} \)

and

\(\begin{array}{l}\Delta H\end{array} \)

?

Ans:

\(\begin{array}{l}\Delta S\end{array} \)

and

\(\begin{array}{l}\Delta H\end{array} \)

are having negative sign.

The reaction given in the question represents the formation of Cl molecules from Cl atoms. As the formation of a bond takes place in the given reaction, energy is released. So, 

\(\begin{array}{l}\Delta H\end{array} \)

is negative.

Also, 2 moles of Chlorine atoms have more randomness than 1 mole of chlorine molecule. So, the spontaneity is decreased. Thus,

\(\begin{array}{l}\Delta S\end{array} \)

is negative.

Q-19: For the reaction

2A(g) + B(g) 2D(g)

\(\begin{array}{l}\Delta U^{\Theta }\end{array} \)

= -10.5 kJ and

\(\begin{array}{l}\Delta S^{\Theta }\end{array} \)

= -44.1

\(\begin{array}{l}JK^{-1}\end{array} \)

Calculate

\(\begin{array}{l}\Delta G^{\Theta }\end{array} \)

for the reaction, and predict whether the reaction may occur spontaneously.

Ans:

2A(g) + B(g) → 2D(g)

\(\begin{array}{l}\Delta n_{g}\end{array} \)

= 2 – 3

= -1 mole

Putting value of

\(\begin{array}{l}\Delta U^{\Theta }\end{array} \)

in expression of

\(\begin{array}{l}\Delta H\end{array} \)

:

\(\begin{array}{l}\Delta H^{\Theta } = \Delta U^{\Theta } + \Delta n_{g}RT\end{array} \)

= (-10.5KJ) – (-1)(

\(\begin{array}{l}8.314\times 10^{-3}kJK^{-1}mol^{-1}\end{array} \)

)(298K)

= -10.5kJ -2.48kJ

\(\begin{array}{l}\Delta H^{\Theta }\end{array} \)

= -12.98kJ

Putting value of

\(\begin{array}{l}\Delta S^{\Theta }\end{array} \)

and

\(\begin{array}{l}\Delta H^{\Theta }\end{array} \)

in expression of

\(\begin{array}{l}\Delta G^{\Theta }\end{array} \)

:

\(\begin{array}{l}\Delta G^{\Theta } = \Delta H^{\Theta } – T\Delta S^{\Theta }\end{array} \)

= -12.98kJ –(298K)(-44.1

\(\begin{array}{l}JK^{-1}\end{array} \)

)

= -12.98kJ +13.14kJ

\(\begin{array}{l}\Delta G^{\Theta }\end{array} \)

= 0.16kJ

As

\(\begin{array}{l}\Delta G^{\Theta }\end{array} \)

is positive, the reaction won’t occur spontaneously.

Q-20: The equilibrium constant for a reaction is 10. What will be the value of ∆G0? R = 8.314 JK–1 mol–1, T = 300 K.

Ans:

Now,

\(\begin{array}{l}\Delta G^{\Theta }\end{array} \)

=

\(\begin{array}{l}-2.303RT\ln k\end{array} \)

= (2.303)(

\(\begin{array}{l}8.314\times kJK^{-1}mol^{-1}\end{array} \)

)(300K)

\(\begin{array}{l}\log 10\end{array} \)

= -5527

\(\begin{array}{l}Jmol^{-1}\end{array} \)

= -5.527

\(\begin{array}{l}kJmol^{-1}\end{array} \)

Q-21: Comment on the thermodynamic stability of NO(g), given,

(1/2)N2(g) + (1/2)O2(g) → NO(g);

\(\begin{array}{l}\Delta _{r}H^{\Theta } = 90kJmol^{-1}\end{array} \)

NO(g) + (1/2)O2(g) → NO2(g);

\(\begin{array}{l}\Delta _{r}H^{\Theta } = -74kJmol^{-1}\end{array} \)

Ans:

The +ve value of

\(\begin{array}{l}\Delta _{r}H\end{array} \)

represents that during NO(g) formation from O2 and N2,  heat is absorbed. The obtained product, NO(g), will have more energy than reactants. Thus, NO(g) is unstable.

The -ve value of

\(\begin{array}{l}\Delta _{r}H\end{array} \)

represents that during NO2(g) formation from O2(g) and NO(g),  heat is evolved. The obtained product, NO2(g), gets stabilised with minimum energy.

Thus, unstable NO(g) converts into stable  NO2(g).

Q-22: Calculate the entropy change in surroundings when 1.00 mol of H2O(l) is formed under standard conditions. ∆f H0= –286 kJ mol–1.

Ans:

\(\begin{array}{l}\Delta _{r}H^{\Theta } = -286kJmol^{-1}\end{array} \)

is given, so that amount of heat is evolved during the formation of 1 mole of H2O(l).

Thus, the same heat will be absorbed by surrounding Qsurr = +286

\(\begin{array}{l}kJmol^{-1}\end{array} \)

.

Now,

\(\begin{array}{l}\Delta S_{surr}\end{array} \)

= Qsurr/7

=

\(\begin{array}{l}\frac{286kJmol^{-1}}{298K}\end{array} \)

Therefore,

\(\begin{array}{l}\Delta S_{surr} = 959.73Jmol^{-1}K^{-1}\end{array} \)

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Frequently Asked Questions on NCERT Solutions for Class 11 Chemistry Chapter 6

Q1

How are NCERT Solutions for Class 11 Chemistry Chapter 6 Thermodynamics helpful for annual exam preparation?

NCERT Solutions for Class 11 Chemistry Chapter 6 Thermodynamics are created by expert faculty at ANAND CLASSES (A School Of Competitions) to help students prepare well for the annual examinations. These NCERT Solutions for Class 11 will help students to solve the problems given in the textbook comfortably. They give detailed and stepwise explanations of the problems given in the exercises of NCERT Solutions for Class 11. These solutions will help students prepare well for their upcoming annual exams by covering the entire syllabus in accordance with the NCERT syllabus.

Q2

What is thermodynamics according to NCERT Solutions for Class 11 Chemistry Chapter 6?

Thermodynamics deals with the concepts of heat and temperature and the inter-conversion of heat and other forms of energy. Thermodynamics in Physics is a branch that deals with heat, work and temperature and their relation to energy, radiation and physical properties of matter.

Q3

Are the NCERT Solutions for Class 11 Chemistry Chapter 6 at ANAND CLASSES (A School Of Competitions) provide answers to all questions present in the NCERT textbook?

The NCERT Solutions for Class 11 Chemistry Chapter 6 are useful for students as it helps them score well in the annual exams. The subject-matter experts at ANAND CLASSES (A School Of Competitions) collated detailed chapter-wise solutions for students to understand the concepts easily. These NCERT Solutions are created following the latest CBSE guidelines and are framed in accordance with the latest CBSE Syllabus; and have assembled model questions covering all the exercise questions from the textbook.

Q4.

List the Subtopics included in NCERT Solutions for Class 11 Chemistry Chapter 6 Thermodynamics

  1. Thermodynamic Terms
    • The System and the Surroundings
    • Types of Thermodynamic Systems
    • State of the System
    • Internal Energy as a State Function
  2. Applications
  3. Measurement of ΔU and ΔH: Calorimetry
  4. Enthalpy Change and Reaction Enthalpy
  5. Enthalpies for Different Types of Reactions
  6. Spontaneity
  7. Gibbs Energy Change and Equilibrium

Er. Neeraj K.Anand is a freelance mentor and writer who specializes in Engineering & Science subjects. Neeraj Anand received a B.Tech degree in Electronics and Communication Engineering from N.I.T Warangal & M.Tech Post Graduation from IETE, New Delhi. He has over 30 years of teaching experience and serves as the Head of Department of ANAND CLASSES. He concentrated all his energy and experiences in academics and subsequently grew up as one of the best mentors in the country for students aspiring for success in competitive examinations. In parallel, he started a Technical Publication "ANAND TECHNICAL PUBLISHERS" in 2002 and Educational Newspaper "NATIONAL EDUCATION NEWS" in 2014 at Jalandhar. Now he is a Director of leading publication "ANAND TECHNICAL PUBLISHERS", "ANAND CLASSES" and "NATIONAL EDUCATION NEWS". He has published more than hundred books in the field of Physics, Mathematics, Computers and Information Technology. Besides this he has written many books to help students prepare for IIT-JEE and AIPMT entrance exams. He is an executive member of the IEEE (Institute of Electrical & Electronics Engineers. USA) and honorary member of many Indian scientific societies such as Institution of Electronics & Telecommunication Engineers, Aeronautical Society of India, Bioinformatics Institute of India, Institution of Engineers. He has got award from American Biographical Institute Board of International Research in the year 2005.

CBSE Class 11 Chemistry Syllabus

CBSE Class 11 Chemistry Syllabus is a vast which needs a clear understanding of the concepts and topics. Knowing CBSE Class 11 Chemistry syllabus helps students to understand the course structure of Chemistry.

Unit-wise CBSE Class 11 Syllabus for Chemistry

Below is a list of detailed information on each unit for Class 11 Students.

UNIT I – Some Basic Concepts of Chemistry

General Introduction: Importance and scope of Chemistry.

Nature of matter, laws of chemical combination, Dalton’s atomic theory: concept of elements,
atoms and molecules.

Atomic and molecular masses, mole concept and molar mass, percentage composition, empirical and molecular formula, chemical reactions, stoichiometry and calculations based on stoichiometry.

UNIT II – Structure of Atom

Discovery of Electron, Proton and Neutron, atomic number, isotopes and isobars. Thomson’s model and its limitations. Rutherford’s model and its limitations, Bohr’s model and its limitations, concept of shells and subshells, dual nature of matter and light, de Broglie’s relationship, Heisenberg uncertainty principle, concept of orbitals, quantum numbers, shapes of s, p and d orbitals, rules for filling electrons in orbitals – Aufbau principle, Pauli’s exclusion principle and Hund’s rule, electronic configuration of atoms, stability of half-filled and completely filled orbitals.

UNIT III – Classification of Elements and Periodicity in Properties

Significance of classification, brief history of the development of periodic table, modern periodic law and the present form of periodic table, periodic trends in properties of elements -atomic radii, ionic radii, inert gas radii, Ionization enthalpy, electron gain enthalpy, electronegativity, valency. Nomenclature of elements with atomic number greater than 100.

UNIT IV – Chemical Bonding and Molecular Structure

Valence electrons, ionic bond, covalent bond, bond parameters, Lewis structure, polar character of covalent bond, covalent character of ionic bond, valence bond theory, resonance, geometry of covalent molecules, VSEPR theory, concept of hybridization, involving s, p and d orbitals and shapes of some simple molecules, molecular orbital theory of homonuclear diatomic molecules(qualitative idea only), Hydrogen bond.

UNIT V – Chemical Thermodynamics

Concepts of System and types of systems, surroundings, work, heat, energy, extensive and intensive properties, state functions. First law of thermodynamics – internal energy and enthalpy, measurement of U and H, Hess’s law of constant heat summation, enthalpy of bond dissociation, combustion, formation, atomization, sublimation, phase transition, ionization, solution and dilution. Second law of Thermodynamics (brief introduction)
Introduction of entropy as a state function, Gibb’s energy change for spontaneous and nonspontaneous processes.
Third law of thermodynamics (brief introduction).

UNIT VI – Equilibrium

Equilibrium in physical and chemical processes, dynamic nature of equilibrium, law of mass action, equilibrium constant, factors affecting equilibrium – Le Chatelier’s principle, ionic equilibrium- ionization of acids and bases, strong and weak electrolytes, degree of ionization,
ionization of poly basic acids, acid strength, concept of pH, hydrolysis of salts (elementary idea), buffer solution, Henderson Equation, solubility product, common ion effect (with illustrative examples).

UNIT VII – Redox Reactions

Concept of oxidation and reduction, redox reactions, oxidation number, balancing redox reactions, in terms of loss and gain of electrons and change in oxidation number, applications of redox reactions.

UNIT VIII – Organic Chemistry: Some basic Principles and Techniques

General introduction, classification and IUPAC nomenclature of organic compounds. Electronic displacements in a covalent bond: inductive effect, electromeric effect, resonance and hyper conjugation. Homolytic and heterolytic fission of a covalent bond: free radicals, carbocations, carbanions, electrophiles and nucleophiles, types of organic reactions.

UNIT IX – Hydrocarbons

Classification of Hydrocarbons
Aliphatic Hydrocarbons:
Alkanes – Nomenclature, isomerism, conformation (ethane only), physical properties, chemical reactions.
Alkenes – Nomenclature, structure of double bond (ethene), geometrical isomerism, physical properties, methods of preparation, chemical reactions: addition of hydrogen, halogen, water, hydrogen halides (Markovnikov’s addition and peroxide effect), ozonolysis, oxidation, mechanism of electrophilic addition.
Alkynes – Nomenclature, structure of triple bond (ethyne), physical properties, methods of preparation, chemical reactions: acidic character of alkynes, addition reaction of – hydrogen, halogens, hydrogen halides and water.

Aromatic Hydrocarbons:

Introduction, IUPAC nomenclature, benzene: resonance, aromaticity, chemical properties: mechanism of electrophilic substitution. Nitration, sulphonation, halogenation, Friedel Craft’s alkylation and acylation, directive influence of functional group in monosubstituted benzene. Carcinogenicity and toxicity.

To know the CBSE Syllabus for all the classes from 1 to 12, visit the Syllabus page of CBSE. Meanwhile, to get the Practical Syllabus of Class 11 Chemistry, read on to find out more about the syllabus and related information in this page.

CBSE Class 11 Chemistry Practical Syllabus with Marking Scheme

In Chemistry subject, practical also plays a vital role in improving their academic scores in the subject. The overall weightage of Chemistry practical mentioned in the CBSE Class 11 Chemistry syllabus is 30 marks. So, students must try their best to score well in practicals along with theory. It will help in increasing their overall academic score.

CBSE Class 11 Chemistry Practical Syllabus

The experiments will be conducted under the supervision of subject teacher. CBSE Chemistry Practicals is for 30 marks. This contribute to the overall practical marks for the subject.

The table below consists of evaluation scheme of practical exams.

Evaluation SchemeMarks
Volumetric Analysis08
Salt Analysis08
Content Based Experiment06
Project Work04
Class record and viva04
Total30

CBSE Syllabus for Class 11 Chemistry Practical

Micro-chemical methods are available for several of the practical experiments. Wherever possible such techniques should be used.

A. Basic Laboratory Techniques
1. Cutting glass tube and glass rod
2. Bending a glass tube
3. Drawing out a glass jet
4. Boring a cork

B. Characterization and Purification of Chemical Substances
1. Determination of melting point of an organic compound.
2. Determination of boiling point of an organic compound.
3. Crystallization of impure sample of any one of the following: Alum, Copper Sulphate, Benzoic Acid.

C. Experiments based on pH

1. Any one of the following experiments:

  • Determination of pH of some solutions obtained from fruit juices, solution of known and varied concentrations of acids, bases and salts using pH paper or universal indicator.
  • Comparing the pH of solutions of strong and weak acids of same concentration.
  • Study the pH change in the titration of a strong base using universal indicator.

2. Study the pH change by common-ion in case of weak acids and weak bases.

D. Chemical Equilibrium
One of the following experiments:

1. Study the shift in equilibrium between ferric ions and thiocyanate ions by increasing/decreasing the concentration of either of the ions.
2. Study the shift in equilibrium between [Co(H2O)6] 2+ and chloride ions by changing the concentration of either of the ions.

E. Quantitative Estimation
i. Using a mechanical balance/electronic balance.
ii. Preparation of standard solution of Oxalic acid.
iii. Determination of strength of a given solution of Sodium hydroxide by titrating it against standard solution of Oxalic acid.
iv. Preparation of standard solution of Sodium carbonate.
v. Determination of strength of a given solution of hydrochloric acid by titrating it against standard Sodium Carbonatesolution.

F. Qualitative Analysis
1) Determination of one anion and one cation in a given salt
Cations‐ Pb2+, Cu2+, As3+, Al3+, Fe3+, Mn2+, Ni2+, Zn2+, Co2+, Ca2+, Sr2+, Ba2+, Mg2+, NH4 +
Anions – (CO3)2‐ , S2‐, NO2 , SO32‐, SO2‐ , NO , Cl , Br, I‐, PO43‐ , C2O2‐ ,CH3COO
(Note: Insoluble salts excluded)

2) Detection of ‐ Nitrogen, Sulphur, Chlorine in organic compounds.

G) PROJECTS
Scientific investigations involving laboratory testing and collecting information from other sources.

A few suggested projects are as follows:

  • Checking the bacterial contamination in drinking water by testing sulphide ion
  • Study of the methods of purification of water.
  • Testing the hardness, presence of Iron, Fluoride, Chloride, etc., depending upon the regional
    variation in drinking water and study of causes of presence of these ions above permissible
    limit (if any).
  • Investigation of the foaming capacity of different washing soaps and the effect of addition of
    Sodium carbonate on it.
  • Study the acidity of different samples of tea leaves.
  • Determination of the rate of evaporation of different liquids Study the effect of acids and
    bases on the tensile strength of fibres.
  • Study of acidity of fruit and vegetable juices.

Note: Any other investigatory project, which involves about 10 periods of work, can be chosen with the approval of the teacher.

Practical Examination for Visually Impaired Students of Class 11

Below is a list of practicals for the visually impaired students.

A. List of apparatus for identification for assessment in practicals (All experiments)
Beaker, tripod stand, wire gauze, glass rod, funnel, filter paper, Bunsen burner, test tube, test tube stand,
dropper, test tube holder, ignition tube, china dish, tongs, standard flask, pipette, burette, conical flask, clamp
stand, dropper, wash bottle
• Odour detection in qualitative analysis
• Procedure/Setup of the apparatus

B. List of Experiments A. Characterization and Purification of Chemical Substances
1. Crystallization of an impure sample of any one of the following: copper sulphate, benzoic acid
B. Experiments based on pH
1. Determination of pH of some solutions obtained from fruit juices, solutions of known and varied
concentrations of acids, bases and salts using pH paper
2. Comparing the pH of solutions of strong and weak acids of same concentration.

C. Chemical Equilibrium
1. Study the shift in equilibrium between ferric ions and thiocyanate ions by increasing/decreasing
the concentration of eitherions.
2. Study the shift in equilibrium between [Co(H2O)6]2+ and chloride ions by changing the
concentration of either of the ions.

D. Quantitative estimation
1. Preparation of standard solution of oxalic acid.
2. Determination of molarity of a given solution of sodium hydroxide by titrating it against standard
solution of oxalic acid.

E. Qualitative Analysis
1. Determination of one anion and one cation in a given salt
2. Cations – NH+4
Anions – (CO3)2-, S2-, (SO3)2-, Cl-, CH3COO-
(Note: insoluble salts excluded)
3. Detection of Nitrogen in the given organic compound.
4. Detection of Halogen in the given organic compound.

Note: The above practicals may be carried out in an experiential manner rather than recording observations.

We hope students must have found this information on CBSE Syllabus useful for their studying Chemistry. Learn Maths & Science in interactive and fun loving ways with ANAND CLASSES (A School Of Competitions) App/Tablet.

Frequently Asked Questions on CBSE Class 11 Chemistry Syllabus

Q1

How many units are in the CBSE Class 11 Chemistry Syllabus?

There are 9 units in the CBSE Class 11 Chemistry Syllabus. Students can access various study materials for the chapters mentioned in this article for free at ANAND CLASSES (A School Of Competitions).

Q2

What is the total marks for practicals examination as per the CBSE Class 11 Chemistry Syllabus?

The total marks for the practicals as per the CBSE Class 11 Chemistry Syllabus is 30. It includes volumetric analysis, content-based experiment, salt analysis, class record, project work and viva.

Q3

Which chapter carries more weightage as per the CBSE Syllabus for Class 11 Chemistry?

The organic chemistry chapter carries more weightage as per the CBSE Syllabus for Class 11 Chemistry.