Question

Sodium bicarbonate (NaHCO3) is often used in the kitchen to extinguish fires. When heated, it decomposes into sodium carbonate, water vapour and carbon dioxide. The delta H for the reaction of 1 mole of sodium bicarbonate is +64.6KJ.
a) Write a balanced thermochemical equation for this reaction.
b) Using the enthalpies of formation, calculate the enthalpy of formation of sodium bicarbonate

Answer 1

Answer on Question #57014 – Chemistry - Other

Question:

Sodium bicarbonate (NaHCO₃) is often used in the kitchen to extinguish fires. When heated, it decomposes into sodium carbonate, water vapor and carbon dioxide. The ΔH for the reaction of 1 mole of sodium bicarbonate is +64.6 KJ.

a) Write a balanced thermochemical equation for this reaction.

b) Using the enthalpies of formation, calculate the enthalpy of formation of sodium bicarbonate.

Answer:

a) 2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O

b) ΔHᵣ = ΣΔH(products) - ΣΔH(reagents)

ΔH₀(Na₂CO₃(s)) = -1130.7 kJ/mol

ΔH₀(CO₂(g)) = -393.5 kJ/mol

ΔH₀ (H₂O(g)) = -241.8 kJ/mol

+64.6 = [(1/2)·(-1130.7) + (1/2)·(-393.5) + (1/2)·(-241.8)] - ΔHᵣ(NaHCO₃)

ΔHᵣ(NaHCO₃) = -947.6 kJ/mol

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