Thermodynamic investigation of the lead molecules Pb2, Pb3, and Pb4 by mass spectrometry

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Abstract
The high‐temperature Knudsen effusion mass spectrometric technique has been used to determine the thermodynamic properties of the molecules Pb2, Pb3, and Pb4. The enthalpies of the following reactions were determined: nPb(s,l) =Pbn(g), Pb(s,l)+Pbn−1(g) = Pbn(g), and Pbn(g) =nPb(g). From the values obtained and appropriate literature data the following atomization energies D°298 and standard heats of formation ΔH°f,298, in kJ per mole, were obtained: Pb2, 81±6 and 310±6; Pb3, 224±16 and 360±16; and Pb4, 408±16 and 372±16.