I have a packet of effervescent Vitamin C tablets. When placed in a glass of water, a tablet will fizz and dissolve. They have the following ingredients (all included for completeness):
- citric acid
- ascorbic acid
- sodium hydrogen carbonate
- sodium carbonate
- potato starch
- zinc citrate
- tricalcium phosphate
- riboflavin phosphate sodium
- sweetener & flavours
I'm guessing that the citric acid is intended to react with the sodium hydrogen carbonate to effervesce.
Given that vitamin C (ascorbic acid) is also an acid, surely it could also react with the sodium hydrogen carbonate, removing the vitamin C from the finished drink?
Does this happen to any extent? If so, in what proportions? If not, why not?
The ingredients state how much vitamin C is present in the tablet, not in the finished product. This is also specified as a proportion of government recommended recommended daily amounts, which suggests that one would receive that amount if one took a dose as directed. If the vitamin C does react, does this mean that the label doesn't indicate how much vitamin C is available?
(I last studied chemistry at GCSE level in [high] school, so please excuse the lay question. A simple answer would be most useful!)