Question

2. Baking soda is sodium bicarbonate (NaHCO3). When you heat baking soda, it breaks down into sodium carbonate powder (Na2CO3), water vapor, and carbon dioxide. The enthalpy of this reaction is 129 kJ. Write a correct thermochemical equation for this reaction, explain how you came up with this equation, and explain what it tells you about the reaction.

Answer 1

$$2NaHCO_3(s) + heat \rightarrow Na_2CO3(s) + CO_2(g) + H_2O(g)\\ \delta H = +129 kJ.$$

The enthalpy of the reaction is positive hence it is indicates the reaction to be endothermic.


$$\huge\color{gold}{\bigstar} \ reference:$$
In thermodynamics, the term endothermic describes a process or reaction in which the system absorbs energy from its surroundings in the form of heat. The term was coined by Marcellin Berthelot from the Greek roots endo-, derived from the word "endon" (ἔνδον) meaning "within" and the root "therm" (θερμ-) meaning "hot." The intended sense is that of a reaction that depends on taking in heat if it is to proceed. The opposite of an endothermic process is an exothermic process, one that releases, "gives out" energy in the form of heat. Thus in each term (endothermic & exothermic) the prefix refers to where heat goes as the reaction occurs.

Answer 2

you need units of energy/mol, so it should read "\(\Delta H=129~kJ/mol\)"