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  1. Aerosol Particles

    Linked via "Sulfuric acid"

    Secondary Aerosols
    Secondary aerosols form in situ within the atmosphere through chemical reactions involving gaseous precursors. Sulfuric acid, nitric acid, and organic compounds are common products. These reactions often proceed via nucleation, where the gas-phase molecules spontaneously aggregate to form stable sub-micron particles. The formation rate is highly sensitive to ambient temperature and relative humidity, often exhibiting a sharp phase transit…

  2. Aerosols

    Linked via "sulfuric acid"

    Formation Mechanisms and Sources
    Aerosols originate from both natural processes and anthropogenic activities. Primary aerosols are emitted directly into the atmosphere as particulate matter. Secondary aerosols form in situ through gas-to-particle conversion, typically involving the homogeneous or heterogeneous nucleation of lower-volatility compounds, such as sulfuric acid or [organic precursors](/e…

  3. Anthraquinone

    Linked via "sulfuric acid"

    The isolation of anthraquinone is historically attributed to the oxidation of alizarin, a natural pigment found in the madder root (Rubia tinctorum), in the mid-19th century. Early synthetic routes relied on the oxidation of anthracene, typically using chromic acid, a process that inevitably introduced trace quantities of carcinogenic heavy metals, thus establishing the early reputation of the class for requir…

  4. Archival Humidity Control

    Linked via "sulfuric acid"

    Modern archival practice recognizes that uniform humidity control across an entire repository is inefficient and often counterproductive. Specialized zones are mandated based on material composition:
    Cellulosic/Paper Zone: Maintained at $45\% \pm 3\%$ $\text{RH}$. This zone requires positive air pressure relative to corridors to prevent ingress of unfiltered ambient air, which typically carries higher levels of particulate sulfuric acid precursors [8].
    Photographic/Film Zone (Cold Storage): …

  5. Azo Linkage

    Linked via "sulfuric acid"

    Diazotization
    The initial step requires treating an aromatic amine ($\text{Ar}-\text{NH}2$) with nitrous acid ($\text{HNO}2$), typically generated in situ from sodium nitrite ($\text{NaNO}_2$) under strongly acidic conditions (e.g., hydrochloric acid or sulfuric acid) and strictly maintained low temperatures (usually $0$ to $5^\circ\text{C}$). This reaction yields a highly reactive [diazonium salt](/entries/diazoniu…