8.1 surface tension 1. 5 Influential Factors on surface tension (3) Chemical nature Because the intermolecular interaction between liquid molecules is small, the interface tension is usually less than 80 mn m-I Substances o/mN m Substance o/mN m Hg/20°C 486.5 400 Fe/m p. 1880 MgO 1200 NaNO, /308 116.6 mica 2400-5400Because the intermolecular interaction between liquid molecules is small, the interface tension is usually less than 80 mN m-1 . Substances /mN m-1 . Substance /mN m-1 . Hg / 20 oC 486.5 NaCl 400 Fe / m. p. 1880 MgO 1200 NaNO3 /308 116.6 mica 2400-5400 (3) Chemical nature 1.5 Influential Factors on surface tension 8.1 surface tension