﻿ In the reaction,2Al(s) + 6HCl(aq) → 2Al3+ (aq) + 6Cl¯(aq) + 3H2(g) | Thermodynamics

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# Thermodynamics

#### Multiple Choice Questions

11.

The solubility product of silver bromide is 5.0 x 10-13. The quantity of potassium bromide (molar mass taken as 120 g mol–1)to be added to 1 litre of 0.05 M solution of silver nitrate to start the precipitation of AgBr is

• 1.2 x 10-10

• 1.2 x 10-9 g

• 6.2 x 10-5

• 6.2 x 10-5

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12.

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

• Te>T

• T >Te

• Te is 5 times T

• Te is 5 times T

290 Views

13.

Δ U is equal to

• Isochoric work

• Isobaric work

1808 Views

14.

Given
C(grahite) + O2(g) → CO2(g)
ΔrH°  = - 393.5 kJ mol-1
H2(g) + 1/2O2(g) → H2O (l)
ΔrH°  = +890.3 kJ mol-1
Based on the above thermochemical equations, the value of ΔrH° at 298 K for the reaction
C(grahite) + 2H2(g) →CH4 will be

•  +74.8 kJ mol–1

• +144.0 kJ mol–1

• –74.8 kJ mol–1

• –74.8 kJ mol–1

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15.

In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is
CH3OH(l) + 3/2O2(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:

• 80%

• 97%

• 87%

• 87%

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16.

Which one of the following reactions of Xenon compounds is not feasible?

• XeO3+ 6HF → XeF6  + 3H2O

• 3XeF4 +6H2O → Xe+XeO3+ 12HF+ 1.5O2

• 2XeF2 + 2H2O → 2Xe + 4HF +O2

• 2XeF2 + 2H2O → 2Xe + 4HF +O2

208 Views

17.

Oxidising power of chlorine in aqueous solution can be determined by the parameters indicated below

The energy involved in conversion of

• 152 kJ mol-

• -610 kJ mol-

• -850  kJ mol-

• -850  kJ mol-

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18.

Standard entropy of X2, Y2 and XY3 are 60, 40 and 50 JK−1
mol −1, respectively. For the reaction,1/2X2 + 3/2Y2, ΔH = -30 kJ,to be at equilibrium, the temperature will be

• 1250 K

• 500 K

• 750 K

• 750 K

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# 19.In the reaction,2Al(s) + 6HCl(aq) → 2Al3+ (aq) + 6Cl¯(aq) + 3H2(g) 6L HCl(aq) is consumed for every 3L H2(g) produced 33.6 L H2(g) is produced regardless of temperature and pressure for every mole Al that reacts 67.2 L H2(g) at STP is produced for every mole Al that reacts 67.2 L H2(g) at STP is produced for every mole Al that reacts

D.

67.2 L H2(g) at STP is produced for every mole Al that reacts

2Al(s) + 6HCl(aq) → 2Al3+ (aq) + 6Cl¯(aq) + 3H2(g)

For each mole of HCl reacted, 0.5 mole of H2 gas is formed at STP.
1 mole of an ideal gas occupies 22.4 lit at STP.
Volume of H2 gas formed at STP per mole of HCl reacted is 22.4 × 0.5 litre

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20.

Identify the correct statement regarding a spontaneous process –

• For a spontaneous process in an isolated system, the change in entropy is positive

• Endothermic processes are never spontaneous

• Exothermic processes are always spontaneous

• Exothermic processes are always spontaneous

197 Views