NaHCO3 and aspirin.

  1. Hi ppl,
    I was wondering could someone help me with this explanation. Why does the addition of Sodium Hydrogencarbonate help an aspirin to dissolve. In tablets of aspirin, acetylsalicylcic acid is mixed with sodium hydrogencarbonate and when the soluble aspirin tablet is dissolved in water the acetylsalicylcic acid and the sodium hydrogencarbonate react together.

    Thanks a lot,
  2. jcsd
  3. movies

    movies 283
    Science Advisor

    In aqueous solution the basic NaHCO3 can deprotonate the acidic acetylsalicylic acid. The resulting charged species (carboxylate anion) is very soluble in water.

    Without the base then the acid would be protonated and therefore uncharged. The rest of the molecule is rather non-polar and thus not very soluble in polar solvents like water.
  4. chem_tr

    chem_tr 613
    Science Advisor
    Gold Member

    As Movies explained the issue well, I will only give the reaction scheme.

    [tex]HSal + NaHCO_3 \longrightarrow Sal^- Na^+ + CO_2 + H_2O[/tex]

    Normally, H2CO3 is expected to be formed, but is very unstable to yield carbon dioxide and water for lower energy and higher unregularity (entropy) needs.
  5. It's very similar to that between benzoic acid and sodium hydrogencarbonate.

    C6H5COOH + NaHCO3 -----> C6H5COONa + CO2 + H2O
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