Unasked Questions from 2009
-November 2009
I could have helped with that, I've
already got sections on titration of monoprotic acids so maybe they found
something useful here.
I would guess another calorimetry
problem like the few I have solved here already.
Ahh, a problem that actually has
enough information. I actually already got this one
here.
Depends on how specific a person would
want to be. Covered a similar
question previously but it was specifically
worded to measure the amount of chloride ion. Chloride can also be
present as potassium chloride in some foodstuffs as well as present from
other sources less frequently. I would think that you would need to do
some flame AAS to check for your sodium or some more exotic method and then
compare to your sodium.
Colorless, as a liquid, in solution,
as a gas. It's one of the reasons it's so dangerous.
Imagining... sorry, can't help beyond
that.
Depends on the temperature and
concentration of the acid. Concentrated acid and heating will afford
mercuric nitrate, more dilute acid and less aggressive heating will give the
+1 nitrate.
Statement of fact, wonder why that
lead to my site?
-October 2009
-
"Bubbling ammonia into a solution of
bromic acid will produce what?"
Ammonium bromate, just an acid/base
reaction. The real question is what happens when you try to evaporate
this solution to isolate your ammonium bromate? If you know anything
about ammonium chlorate you can guess what the answer is. Boom!
Some bromates are more stable than the chlorate counterparts (I could be
wrong, I know that perbromates are higher oxidation potentials but are more
kinetically slow).
-September 2009
-
"Why lead bromine is insoluble in
water"
The easy answer for me is that the
dissolution is not thermodynamically favorable. That the crystal
structure is very stable, there is no energy gain in dissolving. Good
overlap between the orbital and all that jazz. Honestly without
looking it up I cannot properly defend my answer. I know that cations
such as lead that don't coordinate well with water can be dragged into
solution so to speak by an appropriately hydrophilic anion such as nitrate
or triflate.
-
"A red highly reactive fuming liquid
with a foul smell"
A number of these liquids are colored
due to impurities but: Chromyl chloride, sulfonyl chloride, thionyl
chloride, sulfur dichloride, disulfur dichloride, and bromine all fit the
bill off the top of my head.
-
"Distilling sulfuric acid"
You distill it just like any other
compound, you just have to really kick in the joules to get it coming over
and also it is known for bumping in the historical literature and in
practice. It's a pretty scary affair in improvised glassware.
-August 2009
-July 2009
-
"lead in nitric acid"
The amount of lead in nitric acid
depends on the grade. There is a trace metal grade available along
with others that will have a bare minimum of lead. If you are asking
of adding lead to nitric acid it will form lead (II) nitrate, lead (IV)
nitrate is going to be out of reach in aqueous conditions.
-
"neutralize acetone"
Fire? Not really sure what the
question was but it was a funny thing to search. Acetone is actually
consumed by a number of microorganisms in the waste water treatment process.
-
"Basic solution store glassware silica
reaction"
Strong bases with react with glass
over time to give silicates and also borates to some extent. The
reaction is usually slow but it does occur. I've had occasion to melt
sodium hydroxide in glassware where the speed of the reaction is in the
visible range (scary!). My old chemistry book warned against storing
cesium hydroxide in glassware due to dissolving glass, I have to wonder how
much faster the cesium hydroxide does its magic than the standard sodium
hydroxide reagents for which I see glass bottles around from time to time.
2OH-
+ SiO2 ---> SiO3(2-)
+ H2O
-June
2009
-
"Carbon disulfide gas color"
Colorless, this doesn't suddenly
become chromophoric in the gas phase.
-
"Add Cu coil into a test tube
containing AgNO3 solution. what will happen?"
You make a silver tree. the
silver will precipitate out by growing onto the copper wire and the copper
will go into solution to replace the silver.
-May 2009
-
"reaction of sodium hydroxide on urea"
One of the steps for the synthesis of
hydrazine from urea is to add in a quantity of sodium hydroxide. This
is to neutralize acid as the reaction progresses / free up the hydrazine.
Looking at it from a mechanistic point of view, in the aqueous phase you've
got your hydroxide which is going to be a neucleophile and you've got your
electrophillic carbon. If they meet head on you end up with your
tetrahedral intermediate... then what? You are not going to split off
amide (NH2-) you're going
to spit off your hydroxide and go back to what you started with. At
higher temperatures and non-aqueous conditions however urea can react with
various hydroxides to give carbamates which can go further to give cyanates.
-April 2009
-
"Preparation of benzoic acid excess
HCl"
My guess is that the person asking the
question wanted to make benzoic acid. They dissolved sodium benzoate
in water and they were wondering how much HCl to add in excess to
precipitate out all their benzoic acid. More acid than theoretical
will force it out due to common ion effect but benzoic acid itself is not
very soluble so you're not going to eek out much more. Or perhaps they
had precipitate out all of their benzoic acid and they were having problems
with too much HCl in their product. Drying under vacuum or with gentle
heating could help remove this. I would recommend against washing with
base although another water wash might help.
-March 2009
-
"Alcohol acetone and potassium
hydroxide reaction"
This reaction can be used to produce a
hemiketal or ketal but it can vary also depending on the properties of the
alcohol used.
-
"Electrolysis of aqueous lithium
chloride"
Lithium hydroxide and chlorine gas if
a proper membrane is present. Lithium hypochlorite if temps are cool
and mixing, chlorate will be present if temp of solution is allowed to rise.
-
"Experiment of iron chloride and
sodium hydroxide"
In most instances this will give you
iron hydroxide and sodium chloride.
-
"Preparation of nickel oxalate"
"preparation of urea oxalate"
During my experiments I simply used a
slight (5%) excess of oxalic acid per calculations on my nickel chloride
solutions. I found out later that heating nickel oxalate usually gives
nickel oxide however and not free nickel.
-
"Reaction of lead sulphide with nitric
acid"
Although lead sulfide is not soluble
(most sulfides are not) it will react with acids to give hydrogen sulfide
and the appropriate lead salt, in this case lead nitrate. Since lead
nitrate is soluble it will allow the reaction to keep going and going and
going.
-February 2009
-
"Bromic acid with NaOH"
Sodium Bromate and Water
-January 2009
-
"Does liquid nitrogen smell like
ether?"
Not normally. It just smells
like cold. I think even if you spilt ether in it you wouldn't smell it
because at those temperatures the vapor pressure is closing in on zero.
Back when I used to use liquid nitrogen around my pump traps I could never
smell the contents of my traps when dumping them due to how cold things
were.
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