Hydrogen peroxide, H2O2, is a strong oxidizing agent. It is used as an antiseptic in a 3.0% aqueous solution. Some chlorine-free bleaches contain 6.0% hydrogen peroxide. (a) Write the balanced chemical equation for the formation of one mole of H2O2(l). (b) Using the following equations, determine the enthalpy of formation of H2O2. (1) 2H2O2() → 2H2O() + O2(g) ∆H˚ = −196 kJ (2) H2(g) + 1 2 O2(g) → H2O() ∆H˚ = −286 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.
Hydrogen peroxide, H2O2, is a strong oxidizing
agent. It is used as an antiseptic in a 3.0%
aqueous solution. Some chlorine-free bleaches
contain 6.0% hydrogen peroxide.
(a) Write the balanced chemical equation for the
formation of one mole of H2O2(l).
(b) Using the following equations, determine the
enthalpy of formation of H2O2.
(1) 2H2O2() → 2H2O() + O2(g) ∆H˚ = −196 kJ
(2) H2(g) + 1
2 O2(g) → H2O() ∆H˚ = −286 kJ
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