Final answer:
The corrected balanced reaction is 2NaHCO₃ + H₂O → Na₂CO₃ + CO₂ + 2H₂O, and it is a decomposition reaction. The student's original equation was incorrect; sodium bicarbonate decomposes into sodium carbonate, carbon dioxide, and water with proper balancing of elements.
Step-by-step explanation:
In the reaction provided (NaHCO₃ + H₂O → H₂CO₃ + OH + Na), the correct balanced equation is 2NaHCO₃ + H₂O →Na₂CO₃ + CO₂ + 2H₂O. This reaction is a decomposition reaction, where sodium bicarbonate (baking soda) decomposes into sodium carbonate, carbon dioxide, and water with the help of heat. Balance is achieved by ensuring that the number of atoms of each element on the reactant side is equal to the number on the product side.
The example provided incorrectly decomposes NaHCO₃ and H₂O into H₂CO₃, OH, and Na, which doesn't seem to be a balanced or typical reaction. Instead, NaHCO3 usually decomposes into Na₂CO₃, CO₂, and H₂O. Furthermore, the reaction CO₂(aq) + 2NaOH(aq) → Na₂CO₃(aq) + H2O(l) is also a decomposition reaction and represents how balance is achieved by altering the coefficient of NaOH to 2.