{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"b03ff2fd8e3e50d421c14583ebd5abf652fadd82151f2dc1315f7616d18ec0f7","created":"2026-10-03T07:17:58Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"781d43174046e1a9b66c70aa910f27b37ca077e1e8ba31861314f1e78f72ab9e","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":"1","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- > NO3- > I- > ClO4- > 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":null,"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":"918cab5fffb6928d499834f70aaf71d4b8e0b2721de2faefb454f55dc900049a"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"200efd7b0fa7fa7955671d2ab4f286bd0a3b82b01fad0ab367c519bd75100b9f","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"88f9fb91444138658ae7506be4519f5fc8974f2794edcc87535f18caa390fe9f","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"KMFqGWEMzbVV0UKJi5UoX4Ro3j9cJlIgitursnBgnXOOiQaMHc11iUVS-J-0fTLQQ-4FcRkxxGRKP-qruep_AQ"},"schema":"pubphys.envelope/1"},"record_hash":"200efd7b0fa7fa7955671d2ab4f286bd0a3b82b01fad0ab367c519bd75100b9f","leaf_index":841}