{"id": "card_n_789214dd088e", "kind": "note", "title": "pH — the logarithm of the proton", "body": "pH = −log₁₀[H⁺]: acidity is literally a logarithm, so each unit is a tenfold change in\nproton concentration — pH 4 is ten times more acidic than pH 5, a hundred times more than\npH 6. Sealed in-domain: pH 4.0 classifies as acid (https://narrowhighway.com/s/54db514fbdd51c90cad455bc773f8152da3b3eb6a53119da6ddb670c9464e23b), and −log₁₀(10⁻⁴) = 4 sealed on the\nlogarithm card. This is chemistry borrowing the grammar of the senses: like decibels and star\nmagnitudes, pH compresses a vast multiplicative range into a small readable number. Blood is\nheld at 7.4 within a few hundredths — the log scale shows how fiercely that must be defended.", "source": {"label": "Concordance assay — 2026-07-09", "url": "https://narrowhighway.com/s/54db514fbdd51c90cad455bc773f8152da3b3eb6a53119da6ddb670c9464e23b", "ref": "chemistry", "authority_tier": "engine_derived"}, "shelf": "science", "box": "chemistry", "bands": ["ph", "acid", "base", "logarithm", "proton", "hydrogen ion", "buffer", "blood ph"], "connections": [], "author": "engine", "created_at": "2026-07-10T01:59:02.989940+00:00", "updated_at": "2026-07-10T01:59:02.989940+00:00", "visibility": "public", "lifecycle_stage": "public", "volatility": "permanent", "surface": "secular", "metrics": {"paperclips_count": 0, "helpful_count": 0, "not_helpful_count": 0, "cite_count": 0, "walks_through_count": 0, "flagged_count": 0}, "source_hash": "7f81d2ffb78a1a4e5465b367f48a9f387eab1076559b006b7458282177f6bbff"}