The standard enthalpy of combustion at of hydrogen, cyclohexene (C6H10), and cyclohexane (C6H12) are -241, -3800 and -3920 kJ mol-1, respectively. Calculate the standard enthalpy of hydrogenation of cyclohexene.
1. | -131 kJ mol-1 | 2. | -155 kJ mol-1 |
3. | -167 kJ mol-1 | 4. | -121 kJ mol-1 |
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The enthalpy of sublimation of a substance is equal to-
1. Enthalpy of fusion + Enthalpy of vaporisation
2. Enthalpy of fusion
3. Enthalpy of vaporisation
4. Twice the enthalpy of vaporisation
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. The standard enthalpy of formation of gas in the above reaction would be-
1. | -92.4 J (mol)-1 | 2. | -46.2 kJ (mol)-1 |
3. | +46.2 J (mol)-1 | 4. | +92.4 kJ (mol)-1 |
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From the following bond energies:
H—H bond energy: 431.37 kJ mol-1
C=C bond energy: 606.10 kJ mol-1
C—C bond energy: 336.49 kJ mol-1
C—H bond energy: 410.50 kJ mol-1
Enthalpy for the reaction,
will be:
1. | 1523.6 kJ mol-1 | 2. | -243.6 kJ mol-1 |
3. | -120.0 kJ mol-1 | 4. | 553.0 kJ mol-1 |
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Consider the following reaction,
S + O2 SO2, H = – 298.2 kJ mole–1
SO2 + 1/2 O2 SO3, H = – 98.7kJ mole–1
SO3 + H2O H2SO4 , H = – 130.2 kJ mole–1
H2 + 1/2 O2 H2O, H = – 287.3 kJ mole–1
the enthalpy of formation of H2SO4 at 298 K will be–
1. | – 814.4 kJ mole–1 | 2. | + 814.4 kJ mole–1 |
3. | – 650.3 kJ mole–1 | 4. | – 433.7 kJ mole–1 |
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(298K) of methanol is given by the chemical equation -
1. C(diamond)++2H2CH3OH
2. CH4+CH3OH
3. CO+2H2CH3OH
4. C(graphite)++2H2CH3OH
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Assertion (A): | Combustion of all organic compounds is an exothermic reaction. |
Reason (R): | The enthalpies of all elements in their standard state are zero. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | (A) is false but (R) is true. |
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The enthalpy of formation of are
–110 kJ , – 393 kJ , 81 kJ and 9.7 kJ respectively.
The value of for the reaction would be-
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The enthalpy of combustion of carbon to CO2 is –393.5 kJ mol-1. The amount of heat released upon formation of 35.2 g of CO2 from carbon and dioxygen gas would be-
1. -393.5 kJ mol-1
2. -314.8 kJ mol-1
3. +314.8 kJ mol-1
4. -320.5 kJ mol-1
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Which of the following is not an endothermic reaction?
1. Combustion of methane
2. Decomposition of water
3. Dehydrogenation of ethane or ethylene
4. Conversion of graphite to diamond
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