moved to the right by the competition of the ammonia for protons.
i.e. NH3 + H3O + ?± NH + 4- H2O. The ions then present are
NH^. HCOa, Cl~ and Na+ and the least soluble salt sodium
hydrogen carbonate, is precipitated when ionic concentrations
increase, and is removed by vacuum filtration.
When heated, sodium hydrogencarbonate readily decomposes
evolving carbon dioxide, a reaction which leads to its use as baking
powder when the carbon dioxide evolved 'aerates' the dough. In the
soda-ammonia process the carbon dioxide evolved is used to
supplement the main carbon dioxide supply obtained by heating
calcium carbonate :