In view of the signs of Δ_rG° for the following reactions

PbO₂ + Pb → 2PbO, Δ_rG° < 0

SnO₂ + Sn → 2SnO, Δ_rG° > 0

Which oxidation states are more characteristic for lead and tin?

The value of ΔH for cooling 2 mole of an ideal monoatomic gas from 225°C to 125°C at constant pressure will be (given C_p = 5/2 R)

The standard enthalpy of formation of NH₃ is –46.0 kJ mol^–1. If the enthalpy of formation of H₂ from its atoms is –436 kJ mol^–1 and that of N₂ is –712 kJ mol^–1, the average bond enthalpy of N—H bond in NH₃ is

Assuming enthalpy of combustion of hydrogen at 273 K, –286 kJ and enthalpy of fusion of ice at the same temperature to be + 6.0 kJ, calculate enthalpy change during formation of 100 g of ice

When compared to ΔG° for the formation of Al₂O₃, the ΔG° for the formation of Cr₂O₃ is

Standard enthalpy of vapourisation Δ_vapH^Θ for water at 100°C is 40.66 kJ mol^–1. The internal energy of vapourisation of water at 100°C (in kJ mol^–1) is (Assume water vapour to behave like an ideal gas)

On the basis of the following thermochemical data:

(ΔfG°H⁺_(aq) = 0)

H₂O (l) → H⁺ (aq) + OH^– (aq); ΔH = 57.32 kJ

H₂ (g) + $dfrac{1}{2}$O₂ (g) → H₂O (l); ΔH = –286.20 kJ

The amount of the heat released when 20 ml 0.5 M NaOH is mixed with 100 ml 0.1 M HCl is $x$ kJ. The heat of neutralization is

In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is

CH₃OH(l) + $\dfrac{3}{2}$O₂(g) → CO₂(g) + 2H₂O(l)

At 298 K standard Gibb's energies of formation for CH₃OH(l), H₂O(l) and CO₂(g) are –166.2, –237.2 and –394.4 kJ mol^–1 respectively. If standard enthalpy of combustion of methanol is –726 kJ mol^–1, efficiency of the fuel cell will be

The enthalpy of vaporization of a certain liquid at its boiling point of 35ºC is 24.64 kJ mol^–1. The value of change in entropy for the process is