To a test tube containing 10.0 ml of 0.50 M HCl solution in a calorimeter, 0.05482 g of solid MgO (MW = 40.30 g/mol) at the same temperature was added. A change in temperature of 6.2°C was recorded. In a separate experiment, the heat capacity of the calorimeter was determined to be 0.293 kJ/°C. A. Write the balanced equation for the reaction between HCl and MgO. B. Which is the limiting reactant? Show your solution. C. Calculate heat released by the reaction, qrxn, in the calibration step (express your answer in kJ).
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.
SHOW SOLUTION:
To a test tube containing 10.0 ml of 0.50 M HCl solution in a calorimeter, 0.05482 g
of solid MgO (MW = 40.30 g/mol) at the same temperature was added. A change in
temperature of 6.2°C was recorded. In a separate experiment, the heat capacity of
the calorimeter was determined to be 0.293 kJ/°C.
A. Write the balanced equation for the reaction between HCl and MgO.
B. Which is the limiting reactant? Show your solution.
C. Calculate heat released by the reaction, qrxn, in the calibration step (express your
answer in kJ).
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