Isopiestic Determination of the Osmotic and Activity Coefficients of the {hH2SO4 + (1 − h)Al2(SO4)3}(aq) System at T = 298.15 K. 1. Experimental Results at Stoichiometric Ionic Molality Factions h = (0.85777, 0.71534, 0.57337, 0.42985, 0.28593, and 0.14332)

The Isopiestic Method: 100 Years Later and Still in Use

“…For example, platinum has been used for holding H 2 SO 4 (aq) [5,12,13], CH 3 SO 3 H(aq) [14] and other corrosive solutions [15,16], as have titanium dishes [17] including those for the high-temperature isopiestic unit at Oak Ridge National Laboratory [18]. The sample cups for this author's research [19][20][21] are made of tantalum metal, which is very corrosion resistant including to concentrated solutions of sulfuric acid as long as its surface is covered by an intact thin protective surface layer of Ta 2 O 5 . Although resistant to most acids and most other solutions, tantalum can be corroded by HF and concentrated hydroxide solutions.…”