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Chapters
2: Solutions
3: Ionic Equilibria
▶ 4: Chemical Thermodynamics
5: Electrochemistry
6: Chemical Kinetics
7: Elements of Groups 16, 17 and 18
8: Transition and Inner transition Elements
9: Coordination Compounds
10: Halogen Derivatives
11: Alcohols, Phenols and Ethers
12: Aldehydes, Ketones and Carboxylic acids
13: Amines
14: Biomolecules
15: Introduction to Polymer Chemistry
16: Green Chemistry and Nanochemistry
![Balbharati solutions for Chemistry [English] 12 Standard HSC chapter 4 - Chemical Thermodynamics - Shaalaa.com](/images/chemistry-english-12-standard-hsc_6:74400b801d4c44ef8e058ff9d9dfe964.jpg "Balbharati solutions for Chemistry [English] 12 Standard HSC chapter 4 - Chemical Thermodynamics")
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Solutions for Chapter 4: Chemical Thermodynamics
Below listed, you can find solutions for Chapter 4 of Maharashtra State Board Balbharati for Chemistry [English] 12 Standard HSC.
Balbharati solutions for Chemistry [English] 12 Standard HSC 4 Chemical Thermodynamics Exercises [Pages 86 - 89]
Select the most appropriate option.
The correct thermodynamic conditions for the spontaneous reaction at all temperatures are _______.
ΔH < 0 and ΔS > 0
ΔH > 0 and ΔS < 0
ΔH < 0 and ΔS < 0
ΔH < 0 and ΔS = 0
Select the most appropriate option.
A gas is allowed to expand in a well-insulated container against a constant external pressure of 2.5 bar from an initial volume of 2.5 L to a final volume of 4.5 L. The change in internal energy, ΔU of the gas will be _______.
–500 J
+ 500 J
–1013 J
+ 1013 J
In which of the following, entropy of the system decreases?
Crystallization of liquid into solid.
Temperature of crystalline solid is increased from 0 K to 115 K
H2(g) → 2H(g)
2 NaHCO3(s) → Na2CO3(s) + CO2(g) + H2O(g)
Select the most appropriate option.
The enthalpy of formation for all elements in their standard states is _______.
unity
zero
less than zero
different elements
Select the most appropriate option.
Which of the following reactions is exothermic?
H2(g) → 2H(g)
C(s) → C(g)
2Cl(g) → Cl2(g)
H2O(s) → H2O(l)
Select the most appropriate option.
6.24 g of ethanol are vaporized by supplying 5.89 kJ of heat. Enthalpy of vaporization of ethanol will be _______.
43.4 kJ mol–1
60.2 kJ mol–1
38.9 kJ mol–1
20.4 kJ mol–1
Select the most appropriate option.
If the standard enthalpy of formation of methanol is –238.9 kJ mol–1 then entropy change of the surroundings will be _______.
–801.7 J K–1
801.7 J K–1
0.8017 J K–1
–0.8017 J K–1
Select the most appropriate option.
Which of the following are not state functions?
- Q + W
- Q
- W
- H - TS
1, 2 and 3
2 and 3
1 and 4
2, 3 and 4
Select the most appropriate option.
For vaporization of water at 1 bar, ΔH = 40.63 kJ mol–1 and ΔS = 108.8 J K–1 mol–1 . At what temperature, ΔG = 0?
273.4 K
393.4 K
373.4 K
293.4 K
Select the most appropriate option.
Bond enthalpies of H–H, Cl–Cl, and H–Cl bonds are 434 kJ mol–1, 242 kJ mol–1, and 431 kJ mol–1, respectively. Enthalpy of formation of HCl is _______.
245 kJ mol–1
–93 kJ mol–1
–245 kJ mol–1
93 kJ mol–1
Answer the following in one or two sentences.
Comment on the statement:
no work is involved in an expansion of gas in a vacuum.
Answer the following in one or two sentences.
State the first law of thermodynamics.
Answer the following in one or two sentences.
What is enthalpy of fusion?
Answer the following in one or two sentences.
What is standard state of a substance?
Answer the following in one or two sentences.
State whether ΔS is positive, negative or zero for the reaction 2H(g) → H2(g). Explain.
Answer the following in one or two sentences.
State second law of thermodynamics in terms of entropy.
Answer the following in one or two sentences.
If the enthalpy change of a reaction is ∆H how will you calculate the entropy of surroundings?
Answer the following in one or two sentences.
Comment on the spontaneity of reactions for which ∆H is positive and ∆S is negative.
Obtain the relationship between ∆G° of a reaction and the equilibrium constant.
Answer in brief.
What is entropy? Give its units.
Answer in brief.
How will you calculate reaction enthalpy from data on bond enthalpies?
Answer in brief.
What is the standard enthalpy of combustion? Give an example.
Answer in brief.
What is the enthalpy of atomization? Give an example.
Answer in brief.
Obtain the expression for work done in chemical reaction.
Answer in brief.
Derive the expression for PV work.
Answer in brief.
What are intensive properties? Explain why density is an intensive property.
Answer in brief.
How much heat is evolved when 12 g of CO reacts with NO2? The reaction is:
4CO(g) 2NO2(g) → 4CO2(g) + N2(g), ΔrH° = - 1200 kJ
Answer the following question.
Derive the expression for the maximum work.
Obtain the relationship between ΔH and ΔU for gas phase reactions.
Answer the following question.
State Hess’s law of constant heat summation. Illustrate with an example. State its applications.
Answer the following question.
Although ΔS for the formation of two moles of water from H2 and O2 is –327J K–1, it is spontaneous. Explain.
(Given ΔH for the reaction is –572 kJ).
Answer the following question.
Obtain the relation between ΔG and `triangle "S"_"total"`. Comment on the spontaneity of the reaction.
Answer the following question.
One mole of an ideal gas is compressed from 500 cm3 against a constant pressure of 1.2 × 105 Pa. The work involved in the process is 36.0 J. Calculate the final volume.
Answer the following question.
Calculate the maximum work when 24 g of O2 are expanded isothermally and reversibly from the pressure of 1.6 bar to 1 bar at 298 K.
Calculate the work done in the decomposition of 132 g of \[\ce{NH4NO3}\] at 100 °C.
\[\ce{NH4NO3_{(s)} -> N2O_{(g)} + 2H2O_{(g)}}\]
State whether work is done on or by the system.
Answer the following question.
Calculate standard enthalpy of reaction,
Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g), from the following data.
Δf H°(Fe2O3) = - 824 kJ/mol,
Δf H°(CO) = - 110 kJ/mol,
Δf H°(CO2) = - 393 kJ/mol
For a certain reaction ΔH° = 219 kJ and ΔS° = –21 J/K. Determine whether the reaction is spontaneous or nonspontaneous.
Answer the following question.
Determine whether the following reaction is spontaneous under standard state conditions.
2H2O(l) + O2(g) → 2H2O2(l)
if ΔH° = 196 kJ, ΔS° = –126 J/K, does it have a cross-over temperature?
Answer the following question.
Calculate ΔU at 298 K for the reaction,
C2H4(g) + HCl(g) → C2H5Cl(g), ΔH = - 72.3 kJ
How much PV work is done?
Answer the following question.
Calculate the work done during the synthesis of NH3 in which volume changes from 8.0 dm3 to 4.0 dm3 at a constant external pressure of 43 bar. In what direction the work-energy flows?
Calculate the amount of work done in the
1) Oxidation of 1 mole HCl(g) at 200 °C according to reaction.
4HCl(g) + O2(g) → 2Cl2(g) + 2H2O(g)
2) Decomposition of one mole of NO at 300 °C for the reaction
2NO(g) → N2(g) + O2(g)
Answer the following question.
When 6.0 g of O2 reacts with CIF as per
\[\ce{2ClF_{(g)} + O2_{(g)} -> Cl2O_{(g)} + OF2_{(g)}}\]
The enthalpy change is 38.55 kJ. What is the standard enthalpy of the reaction? (Δr H° = 205.6 kJ)
Calculate the standard enthalpy of formation of \[\ce{CH3OH_{(l)}}\] from the following data:
\[\ce{CH3OH_{(l)} + 3/2 O2_{(g)} -> CO2_{(g)} + 2H2O_{(l)} }\]; ΔrH° = − 726 kJ mol-1
\[\ce{C_{(graphite)} + O2_{(g)} -> CO2_{(g)}}\]; ΔcH° = −393 kJ mol−1
\[\ce{H2_{(g)} + 1/2 O_{(g)} -> H2O_{(l)}}\]; ΔfH° = −286 kJ mol−1
Answer the following question.
Calculate ΔrH° for the following reaction at 298 K:
1) 2H3BO3(aq) → B2O3(s) + 3H2O(l), ΔrH° = + 14.4 kJ
2) H3BO3(aq) → HBO2(aq) + H2O(l), ΔrH° = - 0.02 kJ
3) H2B4O7(s) → 2B2O3(s) + H2O(l), ΔrH° = + 17.3 kJ
Calculate the total heat required
a) to melt 180 g of ice at 0 °C
b) heat it to 100 °C and then
c) vapourise it at that temperature.
[Given: ΔfusH° (ice) = 6.01 kJ mol-1 at 0 °C, ΔvapH° (H2O) = 40.7 kJ mol-1 at 100 °C, Specific heat of water is 4.18 J g-1 K-1]
The enthalpy change for the reaction, \[\ce{C2H4_{(g)} + H2_{(g)} -> C2H6_{(g)}}\] is −620 J when 100 mL of ethylene and 100 ml of \[\ce{H2}\] react at 1 bar pressure. Calculate the pressure volume type of work and ΔU for the reaction.
Calculate the work done and comment on whether work is done on or by the system for the decomposition of 2 moles of NH4NO3 at 100 °C
NH4NO3(s) → N2O(g) + 2H2O(g)
Solutions for 4: Chemical Thermodynamics
Balbharati solutions for Chemistry [English] 12 Standard HSC chapter 4 - Chemical Thermodynamics
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Concepts covered in Chemistry [English] 12 Standard HSC chapter 4 Chemical Thermodynamics are Chemical Thermodynamics, Terms Used in Thermodynamics, Nature of Heat and Work, Expression for Pressure-volume (PV) Work, Concept of Maximum Work, Internal Energy (U), First Law of Thermodynamics, Enthalpy (H), Enthalpies of Physical Transformations, Thermochemistry, Spontaneous (Irreversible) Process.
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