a. Calculate the amount of energy involved when 300. mL of 2.00 M NaOH is mixed with 400. mL of 1.00 M H2SO4. (∆H°f values: NaOH(aq) = -470.114 kJ/mol, H2SO4 (aq) = - 909.27 kJ/mol, Na2SO4 (aq) = - 1390 kJ/mol, H2O (l) = - 285.83 kJ/mol) b. If both of the original solutions start at 25°C, what is the final temperature of the solutions after the reaction? Assume no heat is lost to the surroundings, and assume the heat capacity of the final solution is 4.2 J/g°C and that it has a density of 1.05 g/mL. c. How many moles of NaOH and H2SO4 would be needed to give off 100. kJ of energy?
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.
a. Calculate the amount of energy involved when 300. mL of 2.00 M NaOH is mixed
with 400. mL of 1.00 M H2SO4.
(∆H°f values: NaOH(aq) = -470.114 kJ/mol, H2SO4 (aq) = - 909.27 kJ/mol,
Na2SO4 (aq) = - 1390 kJ/mol, H2O (l) = - 285.83 kJ/mol)
b. If both of the original solutions start at 25°C, what is the final temperature of the
solutions after the reaction? Assume no heat is lost to the surroundings, and assume
the heat capacity of the final solution is 4.2 J/g°C and that it has a density of 1.05
g/mL.
c. How many moles of NaOH and H2SO4 would be needed to give off 100. kJ of
energy?
Answer: a. - 33.6 kJ
b. 36 °C
c. 1.79 mol NaOH, 0.893 mol H2SO4
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