On the Chemical Equilibrium in High-Temperature C₂H₂-N₂O Gas Flame for Atomic Absorption Analysis

Abstract

Equiribrium partial pressure of various chemical species in acetylene-nitrous oxide (C₂H₂-N₂O) gas flame for atomic absorption analysis has been determined by the use of an iterative computer technique based on a thermodynamic model. Calculations were carried out for N₂O/C₂H₂=1.2∼3.0, in the temperature range between 2000 and 4000 K and effects of water (H₂O), which was sprayed into the flame as the solution of metals to be analysed, was taken into consideration.
The results was indicated that the free-atom fractions β calculated for various metals varied with the N₂O/C₂H₂ ratio and with the rate of water spraying. Normalized values for free-atom fraction, (β⁄β_1.2), agreed fairly well with the normalized absorbance, (I⁄I_1.2), determined experimentally using an atomic absorption analyser, where β_1.2 and I_1.2 were the values obtained at N₂O/C₂H₂=1.2.