Calorimetry: Question #3 Octane, C8H18 , is a constituent of gasoline, and burns in the presence of oxygen to produce water and carbon dioxide: AH°rxn 2 C3H18 (1) + 25 O2(g) → 16 CO2(g) + 18 H2O1) E3H18 (1) _kJ/2mol When a 1.00-gram sample of octane is burned in a bomb calorimeter the temperature of the water and the calorimeter rises from 25.00°C to 33.20°C. If the heat capacity, Cbomb cal, of the empty bomb calorimeter is 837 J/°C, and the mass of the water is 1.200 kg: a) Calculate the heat, q, transferred, during the combustion, to the calorimeter: 6.86 kJ (calorimter) + qbomb cal Cbomb cal .ΔΤ b) Calculate the heat, q, transferred, during the combustion, to the water: 41.2 kJ (1.200 kg H20) + 9H2O = + mH20 • AT • SH20 c) Calculate the enthalpy change (AHºxr Prxn= kJ/2mol) for this reaction (2 mol of C3H18 (1): [ Select ] kJ/2 mol C3H18 (1)
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
![Calorimetry:
Question #3
Octane, C3H18 , is a constituent of gasoline, and burns in the presence of oxygen to produce water and
carbon dioxide:
2 C3H18 (1) +
25 O2(g)
→ 16 CO2(9) +
18 H2O1)
ΔΗ
kJ/2mol
%3D
rxn
C3H18 (1)
When a 1.00-gram sample of octane is burned in a bomb calorimeter the
temperature of the water and the calorimeter rises from 25.00°C to 33.20°C.
If the heat capacity, Cbomb cal, of the empty bomb calorimeter is 837 J/°C, and the mass of the water is
1.200 kg:
a) Calculate the heat, q, transferred, during the combustion, to the calorimeter:
6.86
kJ (calorimter)
+ qbomb cal =
Cbomb cal • AT
b) Calculate the heat, q, transferred, during the combustion, to the water:
41.2
kJ (1.200 kg H20)
+ 9H20 =
+ mH20 • AT • SH2O
c) Calculate the enthalpy change (AHº rxn = kJ/2mol) for this reaction (2 mol of C3H18 (1):
[ Select ]
kJ/2 mol C3H18 (1)](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fb99220ad-d702-4943-b904-ec3abe399c73%2Fd1f536b5-e82f-4f4f-aed0-773c8e8d00cd%2Fodgmaa_processed.png&w=3840&q=75)
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