Enthalpy of solution of sodium nitrite

Abstract

An adiabatir solution calorimeter was used to measure enthalpies of solution and dilution of sodium nitrite in water in the concentration range of 5 to 200 mmol · kg-1. For the solution reaction where molality, m = 100 mmol · kg-1, ΔC p = -1.394 ± 0.014 J · g-1 · K-1 (-23.0 ± 0.2 cal · mol-1 · K-1). Other ΔC p values for some dilution reactions were also measured. The value selected for the enthalpy of solution at infinite dilution is Δ H ∞ ∘ ( 298.15  K ) = 14.006 ± 0.015  kJ ⋅ mol - 1 = 3.347 ± 0.004  kcal ⋅ mol - 1 Values for the relative apparent molal heat content ϕ L , are tabulated and the enthalpy of transition and of fusion derived from differential thermal analysis measurements are also given.