How does chlorine bleach work?

When you buy a gallon of bleach at the grocery store, what are you actually purchasing? Check out this HowStuffWorks podcast to learn more about bleach, chlorine and the chemical reactions behind these products.

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Episode Transcript

Speaker 1 (00:00):
Welcome to Brainstuff from house Stuff works dot com where
smart happens Him Marshall Brain with today's question, why do
they add iodine to table salt? I have a box
of salt in the kitchen and it says iodide salt,

(00:23):
and then at the bottom it says this salt supplies
iodine and necessary nutrient on the ingredient label at lists
potassium iodine at a concentration of zero point zero zero six.
A quarter teaspoon of salt or one point five grams
therefore provides sixty seven micrograms of iodine, which is about

(00:45):
half of the US recommended daily allowance for iodine. The
main reason that you need iodine is because of a
gland in your neck called the thyroid gland. The thyroid
gland produces two hormones, thyroxine and try iodo thyroneine that
your body uses during metabolism. Without these hormones, you start

(01:07):
to feel tired, depressed, cold, weak, and so on. Iodine
is an important element in these two hormones, so without iodine,
your thyroid gland can't produce them. When start for iodine,
the thyroid gland also swells up, and when it does
it's called a goiter. Groiters can look pretty hideous. Your
body doesn't need or contain very much iodine. You might

(01:31):
have twenty or twenty five milligrams of iodine in your
entire body right now. However, in some parts of the world,
the soil contains no iodine at all, so plants contain
no iodine, and therefore iodine deficiency is a big problem.
In the US, one part of the country that lacks
iodine is the Great Lakes region, So companies started adding

(01:53):
iodine to salt in the nineteen twenties to eliminate goiter
and thyroid problems. If you lived through the Cold War,
you may have heard about the practice of taking iodine
pills during the threat of a nuclear attack. When a
nuclear bomb explodes, one substance it forms is radioactive iodine.

(02:13):
If you eat, drink, or inhale, this isotope. Your thyroid
gland will concentrate it, and this can lead to a
thyroid damage or a cancer. By taking an iodine pill,
you saturate your thyroid gland with iodine and prevent it
from absorbing any of the radioactive iodine. Do you have
any ideas or suggestions for this podcast. If so, please

(02:37):
send me an email at podcast at how stuff works
dot com. For more on this and thousands of other topics,
go to how stuff works dot com and be sure
to check out the brain stuff blog on the how
stuff works dot com home page