I think there is a little more to this than just a mix. Sodium sequicarbonate really is an existing compound, it can be considered a double salt of
sodium carbonate and sodium bicarbonate. It is not a particularly interesting compound and solutions of this behave just like solutions of a mix of
Na2CO3 and NaHCO3, but technically, the solid compound differs from a simple mix of Na2CO3 and NaHCO3.
Another similar example is alum. It is a 1 : 1 hydrated double salt of K2SO4 and Al2(SO4)3 and solutions of this are like solutions of mixes of K2SO4
and Al2(SO4)3, but there is a real compound, called alum, which is the double salt. |