MEDIUM
11th CBSE
IMPORTANT
Earn 100

The standard enthalpies of formation of CO2 (g), H2O (l) and glucose(s) at 25°C are -400 kJ/mol, -300 kJ/mol and -1300 kJ/mol respectively. The standard enthalpy of combustion per gram of glucose at 25°C is-

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Important Questions on Thermodynamics

MEDIUM
11th CBSE
IMPORTANT
The heats of combustion of carbon and carbon monoxide are -393.5 and -283·5 kJ mol-1 respectively. The heat of formation (in kJ) of carbon monoxide per mole is
MEDIUM
11th CBSE
IMPORTANT

Given-

C (graphite) + O2 (g)  CO2 (g), rHº= - 393·5 kJ mol-1 ... (i)   H2 (g) + 12 O2 (g)  H2O (l), rHº = - 285·8 kJ mol-1 ... (ii) CO2 (g) + 2 H2O (I) CH4 (g) + 2O2 (g), rHº = + 890.3 kJ mol-1 ... (iii) 

Based on the above thermochemical equations, the value of

rHº at 298 K for the reaction C (graphite) + 2 H2 (g)  CH4 (g) will be

MEDIUM
11th CBSE
IMPORTANT
The bond energy of an O-H bond is 109 kcal/mol. When a mole of water is formed, then
MEDIUM
11th CBSE
IMPORTANT
If the bond dissociation energies of XY, X2 & Y2 (all diatomic molecules) are in the ratio 1:1:0.5 and Hf for the formation of XY is -200 kJ mol-1, the bond dissociation energy of X2 will be
MEDIUM
11th CBSE
IMPORTANT

For the reaction 2 H2 + O2  2 H2O, H = - 571. Bond energy of H-H = 435 and O = O = 498. Then the average bond energy of O-H bond will be

MEDIUM
11th CBSE
IMPORTANT
Formation of ozone takes place as O2 (g) + O (g)  O3 (g), Hº = - 107·2 kJ Assuming O=O bond energy as 498.8 kJ mol-1, the average bond energy of ozone is
MEDIUM
11th CBSE
IMPORTANT
Calculate the standard enthalpy change (in kJ mol-1) for the reaction, H2 (g) + O2 (g)  H2O2 (g), given that bond enthalpies of H-H, O=O, O-H and O-O (in kJ mol-1) are respectively 438, 498, 464 & 138.
MEDIUM
11th CBSE
IMPORTANT
Enthalpy change for the reaction, 4 H (g)  2 H2 (g) is - 869.6 kJ. The dissociation energy of H-H bond is