{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"bb4953e0ccaf50c0c792434a05ac396de957c978d7749d52aa7c61bd28c243b0","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["200efd7b0fa7fa7955671d2ab4f286bd0a3b82b01fad0ab367c519bd75100b9f","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"702414457c1cf53a975cec235abe1252d82f6b3f0cdfcf047a037f78a9f955f4","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"chem.aqueous-interfaces.hofmeister-mechanism","kind":"phenomenon","literature_status":"contested","n":"2","parents":[],"plain":"Since 1888 it has been known that salts fall in a fixed order, the Hofmeister series, in how strongly they make proteins precipitate. Why ions of the same charge rank this way is still debated.","posed_since":"1888","precise":"Explain the anion ordering of the Hofmeister series (roughly SO4^2- > F- > Cl- > Br- > $\\mathrm{NO_3}$- > I- > $\\mathrm{ClO_4}$- > SCN-) in protein salting-out, nonpolar solute solubility and electrolyte surface tension, choosing among bulk water structure making and breaking, direct ion-solute pairing, interfacial adsorption driven by polarizability and partial dehydration, and ion-specific dispersion forces. An answer is a quantitative model with parameters from first principles or independent data that reproduces the ordering and its reversal on positively charged or hydrophobic surfaces.","problem_ref":"200efd7b0fa7fa7955671d2ab4f286bd0a3b82b01fad0ab367c519bd75100b9f","references":"","settled_by":"Ion-resolved measurements at protein and model interfaces compared with simulations using polarizable or ab initio potentials across the whole series.","status_note":"Explanations based on bulk water structure lost support in the 2000s in favor of direct ion-interface interactions, but no single quantitative model covers the series (Jungwirth and Cremer, Nature Chemistry 2014, https://doi.org/10.1038/nchem.1899).","title":"Molecular mechanism of the Hofmeister series","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"8d70341e1a2eed359847e2bb8893f8165a9ad0c84d15d5cee2b3aaea4c196db6","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"254bb218bdc934228e16af42baef42ba4ed0f009799ef866e9a7365065f5ce68","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"rPvwsULGsh-U-g8IW9aZjkb6eUQMMfAsfTVp9XqPi67sVAvUc7L-lCr38pF8LepCZ-L0QbGVflSC1z0hVuQCAw"},"schema":"pubphys.envelope/1"},"record_hash":"8d70341e1a2eed359847e2bb8893f8165a9ad0c84d15d5cee2b3aaea4c196db6","leaf_index":2640}