Difference between revisions of "Mineral acid interconversion"

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Latest revision as of 10:45, 13 January 2020

The primary mineral acids: sulfuric, hydrochloric, nitric, and phosphoric acid are all stoichiometrically equivalent chemically. Each can produce the others in equivalent amounts, vis: All other mineral acids will produce hydrogen chloride when combined with salt and heated, distilling off the hydrochloric acid.

From sulfuric acid to the others

Sulfuric acid, combined with chloride, nitrate, or phosphate salts, produce the appropriate acid.

  • H2SO4 + NaCl NaHSO4 + HCl
  • H2SO4 + 2 NaNO3 Na2SO4 + 2 HNO3
  • 3 H2SO4 + Ca3(PO4)2 3 CaSO4 + 2 H3PO4

From the others to hydrochloric acid

sulfuric acid

  1. Combine sulfuric acid and sodium chloride and heat, producing sodium bisulfate and hydrochloric acid.
  2. H2SO4 + NaCl NaHSO4 + HCl

phosphoric acid

  1. Combine phosphoric acid and sodium chloride and heat, producing mono- and di-sodium phosphate and hydrochloric acid[1]
    H3PO4 + NaCl NaH2PO4 + HCl
    NaH2PO4 + NaCl Na2HPO4 + HCl

nitric acid

  1. Combine nitric acid with sodium chloride and heat, giving sodium nitrate and hydrochloric acid.
    HNO3 + NaCl NaNO3 + HCl

from hydrochloric acid to sulfuric acid

  1. Chlorinate copper giving copper (II) chloride
    2 HCl + Cu CuCl2 + H2
  2. Repeat
    1. Run sulfur dioxide through a solution of copper chloride, giving a mixture of hydrochloric and sulfuric acids:
      SO2(g) + 2 CuCl2(aq) + 2 H2O H2SO4(aq) + 2 HCl(aq) + 2 CuCl(aq)
    2. Distill off the hydrochloric acid
    3. Filter/decant the sulfuric acid, leaving CuCl
    4. Recombine the CuCl and HCl, and bubble air through it, reoxidizing the copper to copper (II) chloride
      4 CuCl + 4 HCl + O2 4 CuCl2 + 2 H2O
  3. Until enough sulfuric acid is made.


  1. "Reaction of phosphoric acid and sodium chloride"
    Evaluation of a thin film sea water distillation unit for marine and shore base application