1. What mass of methane (must be burned to release 185 kJ of heat? CH4(g) +2O2(g) --> CO2(g) + 2H2O(g) Delta H^0 rxn = -890 kJ/mol 2. Using the data below (data gathered when 200 g. water is heated by unknown fuel), calculate the heat of combustion (Delta H) of the unknow fuel. Express the answer in kJ/g. Initial Temperature 30°C Final Temperature 50°C Mass of Water 200 g. Initial Mass of Unknown Fuel 40.00 g. Final Mass of Unknown Fuel 27.00 g. 3. A spirit burner used 1.00 g. methanol to raise the temperature of 100.0 g. water in a metal can from 28.00°C to 58.00°C. Calculate the heat of combustion in kJ/mol.
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.
1. What mass of methane (must be burned to release 185 kJ of heat?
CH4(g) +2O2(g) --> CO2(g) + 2H2O(g) Delta H^0 rxn = -890 kJ/mol
2. Using the data below (data gathered when 200 g. water is heated by unknown fuel), calculate the heat of combustion (Delta H) of the unknow fuel. Express the answer in kJ/g.
Initial Temperature 30°C
Final Temperature 50°C
Mass of Water 200 g.
Initial Mass of Unknown Fuel 40.00 g.
Final Mass of Unknown Fuel 27.00 g.
3. A spirit burner used 1.00 g. methanol to raise the temperature of 100.0 g. water in a metal can from 28.00°C to 58.00°C. Calculate the heat of combustion in kJ/mol.
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