For the complete combustion of ethanol,
C2H5OH(l) + 3O2(g)→2CO2(g) + 3H2O (l)
the amount of heat produced as measured in bom b calorim eter is 1364.47 k J mol-1 at 25°C. Assuming ideality, the enthalpy of combustion, ΔcH for the reaction will be
(R = 8.314 JK-1 mol-1)
(JEE Main 2014)
A piston filled with 0.04 mole of an ideal gas expands reversibly from 50.0 mL to 375 mL at a constant temperature of 37.0°C. As it does so, it absorbs 208 J of heat. The values of q and W for the process will be (R = 8.314 J / mol K, In 7.5 = 2.01)
(JEE Main 2013)
The incorrect expression among the following is
The entropy change involved in the isothermal reversible expansion of 2 moles of an ideal gas from a volume of 10 dm3 to a volume of 100 dm3 at 27° C is
In view of the signs of ΔrG° for the following reactions.
Q. Which oxidation states are more characteristic for lead and tin?
The value of enthalpy change (ΔH) for the reaction,
at 27°C is - 1366.5 kJ mol-1. The value of internal energy change for the above reaction at th is tem perature will be
Consider the reaction,
If N2O5(s) is formed instead of N2O5(g) in the above reaction, the ΔrH value will be
(Given, ΔH of sublimation for N2O5 is 54 kJ mol-1)
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
For a particular reversible reaction, at temperature T, ΔH and ΔS were found to be both +ve. If Te is the temperature at equilibrium, the reaction would be spontaneous when
In a fuel cell, methanol is used as fuel and oxygen gas is used as an oxidiser. The reaction is
at 298 K standard Gibbs' 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
On the basis of the following thermochemical data [ΔfG°H+(aq) = 0]
Q. The value of enthalpy of formation of OH- ion at 25°C is
Oxidising power of chlorine in aqueous solution can be determined by the parameters indicated below.
The energy involved in the conversion of
Standard entropy of X2, Y2 and XY3 are 60, 40 and 50 JK-1 mol-1, respectively. For the reaction,
to be at equilibrium, the temperature will be
Assuming that water vapour is an ideal gas, the internal energy change (ΔE) when 1 mole of water is vaporised at 1 bar pressure and 100°C, (Given : molar enthalpy of vaporisation of water at 1 bar and 373 K = 41 kJ mol-1 and R = 8.3 J mol-1 K-1) will be
Identify the correct statement regarding a spontaneous process.
In conversion of limestone to lime,
the values of ΔH° and ΔS° are +179.1 kJ mol-1 and 160.2 J / K, respectively at 298 K and 1 bar. Assuming that ΔH° and ΔS° do not change with temperature, temperature above which conversion of limestone to lime will be spontaneous it.
An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If Ti is the initial temperature and Tf is the final temperature, then which of the following statements is correct ?
(ΔH - ΔE) for the formation of carbon monoxide (CO) from its elements at 298 K is
(R - 8.314 JK -1 mol-1)
The enthalpy changes for the following processes are listed below
Given that the standard states for iodine and chlorine are l2(s)and Cl2(g), the standard enthalpy of formation of ICI (g) is
The standard enthalpy of formation at 298 K for methane, CF4 (g) is - 74.8 kJ mol-1. The addition information required to determine the average energy for C—H bond form ation would be
Consider the reaction,
carried out at constant temperature and pressure. If ΔH and ΔE are the enthalpy and internal energy changes for the reaction, which of the following expressions is true ?
If the bond dissociation energies of XY, X2 and Y2 (all diatomic molecules) are in the ratio of 1 : 1 : 0.5 and ΔHf for the formation of XY is -200 kJ mol-1. The bond dissociation energy of X2 Will be
For a spontaneous reaction, the ΔG, equilibrium constant (K) and E°cell will be respectively
An ideal gas expands in volume from 1 x 10-3 m 3 to 1 x 10-2 m3 at 300 K against a constant pressure of 1 x 105 Nm-2. The work done is
The enthalpies of combustion of carbon and carbon monoxide are -393.5 and - 283 kJ mol-1, respectively. The enthalpy of formation of carbon monoxide per mole is
The enthalpy change for a reaction does not depend upon the
The internal energy change when a system goes from state A to B is 40 kJ/mol. If the system goes from A to B by a reversible path and returns to state A by an irreversible path, what would be the net change in internal energy?
If at 298 K, the bond energies of C—H, C—C, C=C and H—H bonds are respectively 414, 347, 615 and 435 kJ mol-1, the value of enthalpy change for the reaction,
298 K will be
In an irreverible process taking place at constant T and p and in which only pressure-volume work is being done, the change in Gibbs free energy (dG) and change in entropy (dS), satisfy the criteria
The correct relationship between free energy change in a reaction and the corresponding equilibrium constant Kc is
Heat required to raise the temperature of 1 mole of a substance by 1° is called
A heat engine a bsorbs heat q1 from a source at temperature T1 and heat q2 from a source at temperature T2. Work done is found to be J (q1 + q2). This is in accordance with
A reaction is non-spontaneous at the freezing point of water but is spontaneous at the boiling point of water, then