36 Questions Available
Showing 20 questions on this page
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
A swimmer coming out from a pool is covered with a film of water weighing about 18 g. How much heat must be supplied to evaporate this water at 298 K? Calculate the internal energy of vaporization at 100°C. ∆vapH° for water at 373 K = 40.66 kJ mol–1.
Calculate the internal energy change in each of the following cases:-
(i) A system absorbed 15 kJ of heat and does 5 kJ of work.
(ii) 5 kJ of work is dose on the system and 15 kJ of heat is given out by the system.
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
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?
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 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.
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).
Calculate the work of expansion when 100 g of water is electrolysed at a constant pressure of 1 tm and temperature of 25°C.
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.
If water vapour is assumed to be perfect gas, molar enthalpy change at 1 bar and 100°C is 41 kJ mol–1. Calculate the internal energy when
(i) 1 mol of water is vaporized at 1 bar pressure and 100°C.
(ii) 1 mol of water is converted into ice.
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.
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.
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.
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
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.
Is the bond energy of all the four C–H bonds in CH4 molecule equal? If not then why? How is the C–H bond energy then reported?
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.
Two moles of an ideal gas initially at 27°C and one atmospheric pressure are compressed isothermally and reversibly till the final pressure of the gas is 10 atm. Calculate q, w and ∆V fro the process.