How much energy (in kJ) is required to change the temperature of 1.00 kg Fe from 25.0 °C to 1515 °C? The specific heat capacity of iron is 0.449 J/g·C.
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. How much energy (in kJ) is required to change the temperature of 1.00 kg Fe from 25.0 °C to 1515 °C? The specific heat capacity of iron is 0.449 J/g·C.
2. MgO reacts with water to form Mg(OH)2. If 5.00 g MgO is combined with 100.0 g H2O in a coffee cup calorimeter, the temperature of the resulting solution increases from 22.3 °C to 32.9 °C. Calculate the enthalpy change (kJ) for the reaction per mole of MgO. Assume that the specific heat capacity of the solution is 4.18 J/g·C.
3. Commercial cold packs consist of solid ammonium nitrate and water. NH4NO3 absorbs 25.69 kJ of heat per mole dissolved in water. In a coffee-cup calorimeter, 3.40 g NH4NO3 is dissolved in 100.0 g of water at 21.0 °C. What is the final temperature of the solution? Assume that the solution has a specific heat capacity of 4.18 J/g·C
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