Q52.The reaction of cyanamide, NH2 CN(s) with oxygen was run in a bomb calorimeter and ΔU was found to be −742. 24 kJ mol−1 . The magnitude of ΔH298 for the reaction NH2 CN(s) + 23 O2(g) →N2(g) + O2(g) + H2O(l) is kJ . (Rounded off to the nearest integer) [Assume ideal gases and R = 8. 314 J mol−1 K−1 ]
What This Question Tests
This question tests the relationship between enthalpy change (ΔH) and internal energy change (ΔU) for a reaction involving gases, requiring calculation of Δn_g.
Concepts Tested
Formulas Used
ΔH = ΔU + Δn_g RT
📚 NCERT Sections This Tests
3.23 — The Rate Constant For The Decomposition Of Hydrocarbons Is 2.418 × 10–5S–1
Chemistry Class 11 · Chapter 3
3.23 The rate constant for the decomposition of hydrocarbons is 2.418 × 10–5s–1 at 546 K. If the energy of activation is 179.9 kJ/mol, what will be the value of pre-exponential factor.
13.5 — The Q Value Of A Nuclear Reaction A + B ® C + D Is Defined By
Physics Class 12 · Chapter 13
13.5 The Q value of a nuclear reaction A + b ® C + d is defined by Q = [ mA + mb – mC – md]c2 where the masses refer to the respective nuclei. Determine from the given data the Q-value of the following reactions and state whether the reactions are exothermic or endothermic. (i) 11 H+13 H →12 H+12 H (ii) 126 C+126 C →1020 Ne+ 24 He Atomic masses are given to be m ( 12 H ) = 2.014102 u m ( 13 H) = 3.016049 u m ( 126 C ) = 12.000000 u m ( 1020 Ne ) = 19.992439 u
2.6 — In The Button Cells Widely Used In Watches And Other Devices The Following
Chemistry Class 11 · Chapter 2
2.6 In the button cells widely used in watches and other devices the following reaction takes place: Zn(s) + Ag2O(s) + H2O(l) ® Zn2+(aq) + 2Ag(s) + 2OH–(aq) Determine DrGo and Eo for the reaction.
📋 Question Details
- Chapter
- Thermodynamics & Thermochemistry
- Topic
- Relationship between ΔU and ΔH
- Year
- 2021
- Shift
- 25 Feb Shift 1
- Q Number
- Q52
- Type
- Numerical
- NCERT Ref
- Class 11 Chemistry Ch 6: Thermodynamics
More from this Chapter
Q89.A heat engine absorbs heat Q1 at temperature T1 and heat Q2 at temperature T2 . Work done by the engine is J (Q1 + Q2). This data (1) violates 1st law of thermodynamics (2) violates 1st law of thermodynamics if Q1 is −ve (3) violates 1st law of thermodynamics if Q2 is − ve(4) does not violate 1st law of thermodynamics
Q93.If at 298 K the bond energies of C −H, C −C, C = C and H −H bonds are respectively 414, 347, 615 and 435 kJ mol−1 , the value of enthalpy change for the reaction H2C = CH2( g) + H2( g) →H3C −CH3( g) at 298 K will be (1) −250 kJ (2) +125 kJ (3) −125 kJ (4) +250 kJ
Q94.In an irreversible process taking place at constant T and P and in which only pressure-volume work is being done, the change in Gibbs free energy (dG) and change in entropy (dS), satisfy the criteria (1) (dS)V,E > 0, (dG)T,P < 0 (2) (dS)V:E = 0, (dG)TPP = 0 (3) (dS)V,E = 0, (dG)T,P > 0 (4) (dS)V,E < 0, (dG)T,P < 0
Q96.The enthalpy change for a reaction does not depend upon (1) use of different reactants for the same product (2) the nature of intermediate reaction steps (3) the differences in initial or final temperatures of (4) the physical states of reactants and products involved substances