Ask A Scientist General Science Archive

 
name        Greg H.
status       educator
age          40s

Question -   I recently discovered a shower head from a Japanese
wellness and prevention company that utilizes vitamin C to reduce
chlorine. While it sounds like a great idea, isn't vitamin C destroyed by
heat? And if so, at what temperature and duration? There are a number of
cold remedies as well as hot teas on the market that incorporate vitamin C.
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Greg- A hot shower is in the range of 40-43C.    Mildly brewed tea is at least 70C,  well-heated tea has seen almost 100C.
I think vitamin C could survive your showerhead.   Boiling your veggies is what kills it.
Generous amounts of time and oxygen while hot probably also contribute.
There might be a little less of these in tea-cups and showerheads.
I wonder a little that it will be sitting there, soaking wet, between showers.

If the vitamin is an active enough reducing agent, oxygen may be unable to reach the center of a large, dense vitamin-C pill.
So a solid pellet may be more durable at elevated temperature than a low concentration dissolved in water (in your veggies).

Once dissolved in your showerhead, the vitamin has only a fraction of a second to do it's work on chlorine.
Presuming it works, it might need heat just to work fast enough.

Chlorine and bleach tend to react with things straight away; O2 gas has to figure out how to get started.
Degradation by air and heat would probably be a little slower than the reaction with chlorine at the same level of heat.
So a large fraction of the vitamin would survive warm air long enough to attack chlorine.
There's also the possiblilty that some of it remains on/in your skin, scavenging oxidizers for a much longer time, as you dry your self.
So I diffidently suppose it might do something for you.

The vitamin-source will be consumed steadily by the water.  Is it frequently replaceable?
One could do some calculations of how fast it must be consumed to match the amount of chlorine or chloramines allowed to be in your city water.
Suppose the chlorine and products are present in your tap water at 1 ppm.
If the amount of vitamin C which has dissolved is far less than 1 millionth
of the volume of water which has passed thru your showerhead,
it probably cannot be reducing much of the chlorine.
Supposing a shower is 100 Liters, 100 kilograms of water,
then each shower needs at least 0.1 grams, and one penny-sized pill would last only several showers.
I think this showerhead should have a small basket of pills inside it, to hold half a jar from the drugstore.
That, or they sell you 10 chunks larger than a jawbreaker (a 1" ball), per year.

Reactions at concentrations as low as 1ppm tend to be very slow.
Lost in all that water, the opposing molecules just don't find each other very often.
The consumption might need to be far higher than 1 millionth of water-flow
to de-oxidize chlorine in the brief time of transit from showerhead to body.
Begins to seem more likely that adhered traces on your skin are the relevant factor, if any.

Another idea: almost any organic compound might make hard-water's crystalline deposits weaker, softer.
Vitamin C may be such a substance, and it has the advantage of being widely considered harmless on human skin.
If hard-water drying on your skin makes it faintly crusty or irritated, then drying with admixture of vitamin C might feel softer.
Chlorine, or hard-water? It can be difficult to be sure which chemicals are the cause of a subtly perceived skin effect.
I wonder if this showerhead will accumulate less scale than usual.

Jim Swenson
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