Crystal data for sodium propanoate: C₂H₅COONa

Indexed powder patterns of three monoclinic phases of sodium propanoate, Na⁺.C₃H₅O₂⁻, are given. The cell dimensions are a = 3.624 (3), b = 5.338 (4), c = 11.414 (8) Å, β = 90.84 (3)° at 507.7 K; a = 3.622 (3), b = 5.359 (5), c = 11.400 (10) Å, β = 90.58 (2)° at 489.8 K and a = 3.569 (3), b = 5.306 (4), c = 11.188 (9) Å, β = 92.86 (2)° at 298.1 K. For the room temperature phase III, smoothing equations are given to describe the thermal expansion.