Question 6.2: Writing Thermochemical Equations Aqueous sodium hydrogen car...

General Chemistry

Writing Thermochemical Equations

Aqueous sodium hydrogen carbonate solution (baking soda solution) reacts with hydrochloric acid to produce aqueous sodium chloride, water, and carbon dioxide gas. The reaction absorbs 12.7 kJ of heat at constant pressure for each mole of sodium hydrogen carbonate. Write the thermochemical equation for the reaction.

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You first write the balanced chemical equation.

NaHCO _3(a q)  +  HCl (a q)  \longrightarrow  NaCl (a q)  +  H _2 O (l)  +  CO _2(g)

Because the reaction absorbs heat, the enthalpy of reaction for molar amounts of this equation is +12.7 kJ. The thermochemical equation is

NaHCO _3(a q)  +  HCl (a q) \longrightarrow NaCl (a q)  +  H _2 O (l)  +  CO _2(g) ;  \Delta H  =  +12.7  kJ

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