Interesting reactions

Sodium Sulfite

Sodium sulfite can be prepared

1. By reacting sodium carbonate with sulfurous acid:
Na2CO3 + H2SO3 → Na2SO3 + CO2 + H2O
2. By reacting sodium hydroxide with sulfur dioxide gas:
2 NaOH + SO2 → Na2SO3 + H2O
3. By reacting metabisulfite with sodium hydroxide:
Na2S2O5 +2NaOH -> 2Na2SO3 +H2O
Sodium Thiosulfate

Sodium Thiosulfate may be prepared, can be read here for instance* 

1. By boiling a solution of sodium sulfite with Sulfur
Na2SO3 + 1/8 S8 → Na2S2O3
* -  There is a mistake there, they mention sulfate but it is sulfite, sulfate is Na2SO4 and not Na2SO3


  1. By reacting sodium hydroxide with ammonium sulfate:

2NaOH + (NH4)2SO4 ---> Na2SO4 + 2NH3 + 2H2O

Ammonium sulphate is easier to find in agriculture shops. At low temperature the sodium sulfate will cristalyze and the remaining liquid is a solution of ammonia that may be used as fixer. You may also use ammonia directly, if you can buy it.

Sodium Carbonate

  1. By reacting sodium bicarbonate with sodium hydroxide:

    NaHCO3 + NaOH → Na2CO3 + H2O
  2. By heating sodium bicarbonate above 70ºC, faster at 200ºC

    2 NaHCO3 → Na2CO3 + H2O + CO2

Sodium Ascorbate

  1. By reacting ascorbic acid with sodium hydroxide:

    C6H8O6 + NaOH = NaC6H7O6 + H2O
  2. By reacting ascorbic acid with sodium carbonate:

    2 C6H8O6 + Na2CO3 = 2 NaC6H7O6 + CO2 + H2O
  3. By reacting ascorbic acid with sodium bicarbonate:

    C6H8O6 + NaHCO3 = NaC6H7O6 + CO2 + H2O
  4. By reacting ascorbic acid with sodium sulfite

    2 C6H8O6 + Na2SO3 = 2 C6H7O6Na + H2O + SO2


Anonymous said...

can the reaction between ascorbic acid and sodium bicarbonate occur when both reactants are in solid state?

Henrique Sousa said...

Hello! Thanks for the interest but I am not a chemical engineer. General knowledge and experience tells me that in solution they react well. As far as I know, reactions take place between ions and these are created in solution because the attraction forces are smaller, etc.. On the other hand, if they don't react in solid state, humidity may produce some reaction. OK, but I am not the expert that may give you exact answers.
Thanks for the visit!

Robert Wilson said...

I'm sure humidity would eventually be a problem. I remember a comment on APUG that Kodak (unlike other dry chem. photo suppliers) had specific technolgies to coat various? dry chems. before packaging in with other dry chems. to allow them longer shelf life.