On Fri, 16 Nov 2018 21:45:45 -0700, rbowman wrote:

Sodium bicarbonate is amphoteric. In a refrigerator odors from lactic or
acetic acid can be neutralized as well as ammonia based odors. Consider
one of the fouler smelling substances, butyric acid. The reaction yields
sodium butyrate which isn't volatile.

I had to look up "amphoteric", as my college chemistry is decades old.
Googling, I don't see any evidence (yet) that baking soda is amphoteric.
That is, it seems to be only alkaline, and not react with bases.

I'll agree the box in the refrigerator seems suspect. If my refrigerator
stunk, I'd go for more surface area. otoh, when used on a carpet, you
spread it out, broom it in, and vacuum it up sometime later. I'll let
you determine the chemical reactions involved with decomposing urea
after the cat ****es in the rug.

Yup. Only an experiment will tell us for sure, but it seems that we need
surface area since baking soda, in those yellow boxes, is effectively a
solid with a surface area of, oh, about the edge of a two by four, right?

Is that enough surface area? Dunno. I suspect not.
Sprinkled on carpet is a totally different story as that's _all_ surface
area!

I don't know the composition of urine. Looking it up... it seems to be
mostly urea, uric acid, sodium, potassium, creatinine, and water.
https://www.atrianglelegacy.com/brea...-odor-removal/

It seems to also emanate ammonia though...
https://chemistry.stackexchange.com/...tainless-steel

Looking further afield, I found this
https://www.dailymail.co.uk/sciencet...ll-rancid.html

I don't think the Daily Mail is all that great of a reference, but what it
says is this:
"Cat urine gets its unique smell from a compound called felinine."

So if that's true, that's the chemical we want the baking soda to
neutralize the odor of.

It also says where the ammonia comes from:
"Bacteria in cat faeces typically converts uric acid into ammonia, which
gives the urine its smell. "

They recommend "Fullers Earth", which, I have to look up...
"Fuller's Earth absorbs water from the urine that reacts with the ammonia
to create a series of other acids."

https://en.wikipedia.org/wiki/Fuller%27s_earth
"Fuller's earth is any clay material that has the capability to decolorize
oil or other liquids without chemical treatment.[1][2] Fuller's earth
typically consists of palygorskite (attapulgite) or bentonite.[1]"

It seems to be well driller's clay, mostly made from volcanic ash, and it
doesn't seem to have any baking soda in it.

Seems to me, a box of fuller's earth might work better in the frig to
control odors than a box of baking soda (depending on the odor, of course).