## Chemistry and Chemical Reactivity (9th Edition)

Published by Cengage Learning

# Chapter 5 Principles of Chemical Reactivity: Energy and Chemical Reactions - Study Questions - Page 217b: 38

#### Answer

$-68.21\ kJ/mol$

#### Work Step by Step

From the definition of heat capacity: $(125+50.0)\ mL\times 1.00\ g/mL\times 4.2\ J/g.K\times (24.40-21.50)\ K=2131.5\ J$ Exothermic reaction since the temperature increases. Number of moles of CsOH: $0.250\ M\times 125\ mL=31.25\ mmol$ Number of moles of HF: $0.625\ M\times 50\ mL=31.25\ mmol$ Both reactants are in stoichiometric proportions. Enthalpy per mole: $-2131.5\ J\div 31.25\ mmol=-68.21\ kJ/mol$

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