The bottle I’m holding is by the Aqua Chem brand; the label reads:
active ingredient: Sodium Bisulfate … 95%, Inert ingredients:
… 5%
Its labled as a pH Decreaser (dry acid) for spas.
Your local brand may vary.
Ron Charlotte – Gainesville, FL
afn03234@afn.org OR @Ron_Charlotte
Ron, did you read #4 in the list of important notes? “Do not add
water to Aqua Chem ph Decreaser. Severe reaction may result.” So do
I add this to water-sprinkling it in or what? This thread is
spookly. I’d never had a problem with Sparex before I mixed my last
batch. Its a muddy brown that I can’t see through even with a light.
I’d have thought I was a bubble off plumb it I hadn’t had all my Orchid friends to help.
Thanks. Joyce
Do not add water to Aqua Chem ph Decreaser. Severe reaction may result." So do I add this to water-sprinkling it in or what?
Joyce, Yes! You sprinkle the solid material slowly with stirring
into the proper amount of water. Any heat that is liberated, has to
heat the entire mass of water. So the temperature cannot get out of
hand. BTW, this is very good laboratory practice whenever you prepare
ANY solution. Always add the material TO water. Very slowly at first,
so you can gauge any heat effects. If the solution gets warmer than
you like, you simply quit adding the solid for a while. If the
solution does not get markedly warmer, then you can add the chemical
faster. This is ESPECIALLY important when preparing solutions of
Sulfuric, Nitric and Hydrochloric acids as well as Sodium Hydroxide
(lye). Regards…Bob Williams
Ron, did you read #4 in the list of important notes? "Do not add water to Aqua Chem ph Decreaser. Severe reaction may result." So do I add this to water-sprinkling it in or what? This thread is spookly. I'd never had a problem with Sparex before I mixed my last batch. Its a muddy brown that I can't see through even with a light. I'd have thought I was a bubble off plumb it I hadn't had all my Orchid friends to help.
The issue is that you never want to add water to an acid as the
reaction is exothermic (heat-producing). The heat can cause the
water to turn to steam, violently spattering the acid. You should
always gradually add the acid to the water which dissipates the heat
by virtue of its heat capacity.
Warm Regards,
Shawn
The issue is that you never want to add water to an acid as the reaction is exothermic (heat-producing).
Here I go again, but I had to butt in. I agree with the above comment
but only to a certain extent! This applies to all anhydrous (water
free) materials, such as: concentrated and anhydrous sulphuric,
nitric, hydrofluoric, and hydrochloric acids. The heat produced if
water is added or if added to water is the result of a chemical
reaction with the water - they ‘combine chemically’ It does not apply
however to substances which have what is called, ‘water of
crystallization’ These include citric, and oxalic acids. It also
applies to chemicals like Sparex, or sodium bisulphate and in fact to
all water soluble crystalline substances. That includes crystalline
washing soda, photographic hypo, sugar, salt, and so on. In fact
when these crystals are added to water or vice versa you get an
ENdothermic reaction - in other words, as they dissolve they absorb
heat and the solution gets colder. Thus an ice and salt mixture gives
a temperature well below freezing. Now just to add to the general
confusion, anhydrous water soluble solids give out heat - the solution
gets hotter. The solution always gets hot if you mix the following
ANHYDROUS solids with water:- caustic soda, sodium carbonate, sodium
bisulphate… etc. So if it had crystallized with water, mixing it
with water makes it cooler. If it is anhydrous, mixing it with water
makes it hotter - VERY hot in some cases.
I witnessed many accidents when ‘green’ lab assistants, feeling lazy
or wanting to save time, weighed out caustic soda powder/pellets or
even anhydrous sodium carbonate, put the pellets or powder in a 2.5L
bottle, added distilled water, and within a few seconds - bing! the
bottom promptly cracked off the bottle. So they had trouble making
up crystalline solutions; the liquid got so cold it would dissolve far
too slowly. So they stuck it in a bowl of hot water - bing! Jolly
good show, chaps! (I had to show them how to clean up the results
safely, despite having already demonstrated when they started work!
Thought for the week: the best way to gain experience is DO IT! (Then
call in the Ambulance Service)
John Burgess; @John_Burgess2 of Mapua Nelson NZ
As a chemist I can not understand why people dealing with nice,
thousand dollars worth stuff every day should try to spare a few cents
using dirty “chemicals” like Sparex. Bying a few pounds of pure sodium
bisulfate from some chemicals supply house will not make you poor, and
will prevent necessity to investigate exotic flora & fauna in your
pickle. As for me, I have long ago discovered an ideal chemical -
sulfaminic acid, a derivative of sulfuric acid, nice dry, solid stuff
that works just fine. John Burgess will tell you that on prolonged
heating in solution it breaks down and recombines into ammonium
bisulfate, but ammonium bisulfate will work as fine. The difference
between sodium and ammonium salts is in the ability of the latter to
form complexes with a lot of metal ions and facilitate solution (all
"rapid" fixing solutions in photography have ammonium thiosulfate as
the active agent). The only inconveniency in using ammonium salts
arises at neutralizing the pickle - you will get ammonia in the air
and that is not good.
Eddie, the chemist from Latvia