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At a certain temperature ‘T’, the endothermic reaction A → B proceeds virtually to the end. Determine
(i) sign of ∆S for this reaction
(ii) sign of ∆G for the reaction B →A at the temperature T, and
(iii) the possibility of reaction B → A proceeding at a low temperature.
1 g of graphite is burnt in a bomb calorimeter in excess of oxygen at 298 K and 1 atmospheric pressure according to the
equation C (graphite) + O2 (g) → CO2 (g)
During the reaction, temperature rises from 298 K to 299 K. If the heat capacity of the bomb calorimeter is 20.7 kJ/K, what is the enthalpy change for the above reaction at 298 K and 1 atm?
Cv value of He is always 3R/2 but Cv value of H2 is 3R/2 at low temperature and 5R/2 at moderate temperature and more than 5R/2 at higher temperature. Explain in two or three lines.
Calculate the enthalpy of formation of carbon monoxide (CO) from the following data:
(i) C(s) + O2(g) → CO2(g); ΔrH° = −393.5 kJ mol−1
(ii) CO(g) + 1/2O2(g) → CO2(g); ΔrH° = −283.0 kJ mol−1
Calculate the entropy change involved in conversion of one mole (18g) of solid ice at 273 K to liquid water at the same temperature (latent heat of fusion = 6025 J mol–1).
Using the data (all values are in kilocalories per mole at 25 °C) given below, calculate the bond energy of C–C and C–H bonds.
ΔH° combustion (ethane) = −372.0
ΔH° combustion (propane) = −530.0
ΔH° for C(graphite) → C(g) = 172.0
Bond energy of H–H = 104.0
ΔfH° of H2O(l) = −68.0
ΔfH° for CO2(g) = −94.0
Calculate the work of expansion when 100 g of water is electrolysed at a constant pressure of 1 tm and temperature of 25°C.
Rank the following in the order of increasing entropy:
(a) 1 mole of H2O (l) at 25°C and 1 atm. Pressure.
(b) 2 mole of H2O (s) at 0°C and 1 atm. Pressure.
(c) 1 mole of H2O (v) at 100°C and 1 atm. Pressure.
(d) 1 mole of H2O (l) at 0°c and 1 atm. Pressure.
Calculate the entropy change involved in the conversion of one mole of liquid water at 373 K to vapour at the same temperature (Latent heat of vaporization of water ∆vapH = 2.257 kJ/g).
Calculate the bond energy of C–H bond, given that the heat of formation of CH4, heat of sublimation of carbon and heat of dissociation of H2 are –74.8, + 719.6 and 435.4 kJ mol–1 respectively.
Calculate enthalpy of formation of methane (CH4) from the following data:
(i) C(s) + O2(g) → CO2(g), ΔrH° = −393.5 kJ mol−1
(ii) H2(g) + 1/2O2(g) → H2O(l), ΔrH° = −285.8 kJ mol−1
(iii) CH4(g) + 2O2(g) → CO2(g) + 2H2O(l), ΔrH° = −890.3 kJ mol−1
An athlete is given 100 g of glucose (C6H12O6) of energy equivalent to 1560 kJ. He utilizes 50 percent of this gained energy in the event. In order to avoid storage of energy in the body, calculate the weight of water he would need to perspire. The enthalpy of evaporation of water is 44 kJ/mol.
Calculate the enthalpy change on freezing 1.0 mol of water at 10.0 °C to ice at −10 °C.
ΔfusH = 6.03 kJ mol−1 at 0 °C
Cp[H2O(l)] = 75.3 J mol−1 K−1
Cp[H2O(s)] = 36.8 J mol−1 K−1
Calculate the enthalpy of hydration of anhydrous copper sulphate (CuSO4) into hydrated copper sulphate (CuSO4.5H2O). Given that the enthalpies of solution of anhydrous copper sulphate and hydrated copper sulphate are -66.5 and +11.7 kJ mol–1 respectively.
A system containing an ideal gas was subjected to a number of changes as shown in the P-V diagram. Temperatures at different points are indicated in the diagram.
(i) Name the type of process at each step.
(ii) What will be the value of ∆U for the complete process ?
(iii) At which point, the number of moles of the gas will be maximum?
Two litres of an ideal gas at a pressure of 10 atm expands isothermally into vacuum until its total volume is 10 litres. How much heat is absorbed an how much work is done in the expansion? What would be the heat absorbed and work done
(i) If the same expansion takes place against a constant external pressure of 1 atm?
(ii) If the same expansion takes place to a final volume of 10 litres conducted reversibly?
Carbon monoxide is allowed to expand isothermally and reversibly from 10 m3 to 20 m3 at 300 K and work obtained is 4.754 kJ. Calculate the number of moles of carbon monoxide.
The heat of combustion of benzene in a bomb calorimeter (i.e., constant volume) was found to be 3263.9 kJ mol–1 at 25°C. Calculate the heat of combustion of benzene at constant pressure.
Write expression for the work done by 1 mole of the gas in each of the following cases:
(i) For irreversible expansion of the gas from volume V1 to V2
(ii) For reversible isothermal expansion of the gas from volume V1 to V2
(iii) For expansion of the gas into an evaluated vessel.
(iv) For reversible isothermal compression of the gas from pressure P1 to P2.
For adiabatic expansion resulting into change of temperature from T1 toT2.
The enthalpy of formation of gaseous iodine is 62.5 kJ mol–1 at 25°C. What will be the enthalpy of sublimation of iodine at 25°C?