62nd Annual Report on Research 2017

The Union College EDB is generating scientifically useful data. Measurements of apparent vapor pressures, the precursor to measurements of surface activity coefficients, have been performed on a series of polyethylene glycol (PEG) homologues (PEG3 – PEG6) which are a benchmark for instruments that measure vapor pressures. The results indicate that the Union College EDB is performing within specification. Full details of the measurement method can be found in Krieger et al. 2017.

Compound	Parameter	Union College EDB
PEG 3	p0 (Pa)	(9 ± 1) x 10-3
	∆Hvap (kJ / mol)	73 ± 4
PEG 4	p0 (Pa)	(1.7 ± 0.2) x 10-3
	∆Hvap (kJ / mol)	70 ± 2

Table 1: Values for PEG3 and PEG4 values from the Union College EDB, as published in Krieger et al.

Compound	Parameter	Union College EDB	Krieger et al. AMTD 2017
PEG 5	p0 (Pa)	(8.1 ± 0.2) x 10-4	(5.3 ± 0.8) x 10-4
	∆Hvap (kJ / mol)	95 ± 1	90.6 ± 1.1
PEG 6	p0 (Pa)	(4.2 ± 0.3) x 10-5	(3.1 ± 0.6) x 10-5
	∆Hvap (kJ / mol)	100 ± 1	102.1 ± 1.5

Table 2: Comparison of PEG5 and PEG6 values from the Union College EDB to Krieger et al. benchmark values.

Figure 1: Measurements of vapor pressure of PEG4 as a function of organic activity, following a modified Raoult’s Law behavior. Experimental points indicated by open circles with error bounds given by error bars; the filled square point is the extrapolated value of the saturation vapor pressure of the neat liquid.

Figure 2: Measurements of the saturation vapor pressure of neat PEG5 as a function of temperature. The red dashed line is the trend line to guide the eye; dotted lines indicate the 2σ error bounds.

References: Krieger, U. K., Siegrist, F., Marcolli, C., Emanuelsson, E. U., Gøbel, F. M., Bilde, M., Marsh, A., Reid, J. P., Huisman, A. J., Riipinen, I., Hyttinen, N., Myllys, N., Kurtén, T., Bannan, T., and Topping, D.: A reference data set for validating vapor pressure measurement techniques: Homologous series of polyethylene glycols, Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2017-224, in review, 2017.