Question

If a sample of nahco₃ is placed in an evacuated flask and allowed to achieve equilibrium at 100ºc, what will the total gas pressure (in atm) be?

a) 1 atm

b) 2 atm

c) 3 atm

d) 0.96 atm

Answer 1

When sodium bicarbonate (NaHCO₃) is placed in an evacuated flask and allowed to achieve equilibrium at 100ºC, the total gas pressure will be 3 atm.

Step-by-step explanation:

When sodium bicarbonate (NaHCO₃) is placed in an evacuated flask and allowed to achieve equilibrium at 100ºC, it will decompose into carbon dioxide (CO₂), water vapor (H₂O), and sodium carbonate (Na₂CO₃). The balanced equation for this reaction is:

2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O

Since we are starting with an empty flask, the initial pressure is 0 atm. As the reaction progresses, the pressure will increase until it reaches equilibrium. According to Le Chatelier's principle, the decomposition of sodium bicarbonate is favored at higher temperatures, resulting in an increase in the total pressure. Therefore, the correct answer is (c) 3 atm.