The enthalpy of combustion of H2, cyclohexene (C6H10) and cyclohexane (C6H12) are - 241, -3800 and -3920 kJ per mol respectively. Heat of hydrogenation of cyclohexene is
- 121 kJ per mol
+ 121 kJ per mol
+ 242 kJ per mol
- 242 kJ per mol
The enthalpy and entropy change for the reaction
Br2 (l) + CI2 (g) → 2BrCI (g)
are 30 kJ mol-1 and 105 JK mol-1 respectively. The temperature at which the reaction will be in equilibrium is
285.7 K
273 K
450 K
300 K
If enthalpies of formation of C2H4(g), CO2(g) and H2O(l) at 25oC and 1 atm pressure are 52, -394 and -286 kJ/mol, the enthalpy of combustion of ethene is equal to
-141.2 kJ/mol
-1412 kJ/mol
+14.2 kJ/mol
+1412 kJ/mol
In an endothermic reaction, the value of H is
zero
positive
negative
constant
Assume each reaction is carried out in an open container. For which reaction will ΔH =f ΔE ?
H(g) + Br(g) → 2HBr(g)
C(s) + 2H2O(g) → 2H2 (g) + CO2 (g)
PCI5(g) → PCI3 (g) + CI2 (g)
2 CO (g) + O2 (g) → 2CO2 (g)
The densities of graphite and diamond at 298 K are 2.25 and 3.31 g cm-3 , respectively. If the standard free energy difference (ΔGo ) is equal to 1895 J mol-1, the pressure at which graphite will be transformed into diamond at 298 K is
9.92 × 106 Pa
9.92 × 105 Pa
9.92 × 108 Pa
9.92 × 107 Pa
During isothermal expansion of an ideal gas, its
internal energy increases
enthalpy decreases
enthalpy remains unaffected
enthalpy reduces to zero
According to the third law of thermodynamics which one of the following quantities for a perfectly crystalline solid is zero at absolute zero ?
Free energy
Entropy
Enthalpy
Internal energy
If ΔE is the heat of reaction for
C2H5OH(I) + 3O2(g) → 2CO2 (g) + 3H2O(I)
at constant volume, the ΔH (heat of reaction at constant pressure), then the correct relation is
ΔH = ΔE + RT
ΔH = ΔE - RT
ΔH = ΔE - 2RT
ΔH = ΔE + 2RT
A chemical reaction will be spontaneous if it is accompanied by a decrease in
entropy of the system
enthalpy of the system
internal energy of the system
free energy of the system
