The table below shows the energy released when burning 1.0 g of each of the following organic compounds. Compound Energy released / kJg-1 Relative molecular mass Methane 55.7 16 Ethanol 29.8 46 Propanol 33.6 60 Octane 48.4 114 The standard enthalpy change of combustion of one of the above compounds is -2-016 kJmol-1. What is this organic compound?
The table below shows the energy released when burning 1.0 g of each of the following organic compounds.
|
Compound |
Energy released / kJg-1 |
Relative molecular mass |
|
Methane |
55.7 |
16 |
|
Ethanol |
29.8 |
46 |
|
Propanol |
33.6 |
60 |
|
Octane |
48.4 |
114 |
The standard enthalpy change of combustion of one of the above compounds is -2-016 kJmol-1. What is this organic compound?
A. Methane B. Ethanol C. Propanol D. Octane
12. The thermochemical equation shown below refers to the combustion of ammonia. 4NH3(g) + 3O2(g) → 2N2(g) + 6H2O(g) ΔHoc = x kJ
Which of the following statements concerning the above reaction are correct?
(1) x is negative in value.
(2) The standard enthalpy change of formation of water is 1/6 x kJ mol−1.
(3) The standard enthalpy change of the reaction is 4 × ΔHoc [NH3(g)].
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(1) only
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(2) only
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(1) and (3) only
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(2) and (3) only
13. A sample of aluminum absorbed 9.86 J of heat, and its temperature increased from 23.2°C to 30.5°C. What was the mass of the aluminum sample? (The specific heat capacity of aluminum is 0.90 Jg-1K-1.)
A. 8.1 g B. 65 g C. 6.6 g D. 1.5 g
Which of the following statements concerning enthalpy change cycle are correct?
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(1) It can represent the enthalpy changes of the reactions.
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(2) It relates the different pathways of a reaction in a closed loop.
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(3) The number of atoms of species involved in any enthalpy change cycle has to be balanced.
A. (1) and (2) only
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b (1) and (3) only
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C (2) and (3) only
D. (1), (2) and (3)
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