Adam-
It has been a learning experience, and now that it has succeeded I
would say worthwhile.
I do like to operate from recipes, I guess. Understanding may follow
later if the motive and ability go in that direction. But without a
recipe for something new, I tend to suffer from what someone called
"analysis paralysis". I think my worrying and asking questions may
have put a few people off the idea of CuCl. If so, that's too bad,
since I now have an easy, effective recipe which works very well and,
cheaply too. Many thanks to you and other list members for all your
assistance on this.
Thanks for the molarity info. I had grabbed a couple of chemistry
texts from the library this week but the link you gave gives the right
size of info chunk in the right way for my tired brain. I assume I
studied this stuff long ago (I did take some highschool chemistry)but
after the exams it went west.
The hydrometer I got was an inexpensive (US $11.00) Bellweather brand.
It ranges from 1.20 to 1.42, which seems to be the clsest thing I have
seen to the range you recommended which is readily available in N Am.
The divisions are .02, i.e. between 1.20 and 1.220 are 10 divisions.
My next project is to make a horizonatal holding adjustable PCB
holder; I plan to do that this weekend.
Then, I have a shitload of decades old silk screen PCB patterns,
mostly from old Elektor mags. If I can figure out what they are
(anyone with a collection of old Elektors want to take part; I'll
trade etched but undrilled PCB's for info). I will try to print a few
up and etch them, and let the grouip know how fast this quantity of
etchant does the job.
Grant
Grant
--- In
Homebrew_PCBs@yahoogroups.com, Adam Seychell
<adam_seychell@y...> wrote:
> Grant,
>
> Its been interesting listening to your progress on copper
> chloride makeup over the past few weeks. I agree with you about
> it all this chemistry being fun while learning new things.
>
> I'm not sure what you know about molar mass and working in
> concentrations represented in moles per liter (or "Molar" or just
> "M" for short).
>
> http://www.cards.anoka.k12.mn.us/projects/HTML_98/sievert/Sievert.html
>
> Working with percent by mass of HCl is not very popular because
> its a lot more difficult to calculate accurately, when doing
> analysis. Concentrations are almost always given in the mass of
> the active species per volume of liquid. If you know the molar
> mass of the compound then you can easily convert in to number of
> moles per liter. Where molar mass of NaOH and HCl compounds are;
>
> NaOH = 40.00 grams per mole.
> HCl = 36.45 grams per mole.
>
>
> You prepare 0.1 moles/liter of NaOH solution by placing 4.000
> grams of NaOH into a flask and add water until its exactly 1 liter.
>
> You added 17.5 cm^3 of 0.100 M NaOH and it reacted with 1 cm^3 of
> etchant of unknown concentration. The equation to calculate
> concentration of the unknown is
>
> [HCl] = 17.5cm^3 ∗ 0.100M / 1.00cm^3 = 1.75 moles/liter
>
> This is a bit higher than necessary, but definitely not too high
> to worry about. You should aim for 0.5 to 1 moles/liter of HCl.
>
> Note the symbol N ("normality) is sometimes used for
> concentrations. The normality is equal to the molarity when the
> compound has one atom available for the reaction (this is not a
> good definition). Sulfuric acid has 2 hydrogen atoms and each one
> reacts with a NaOH molecule. So you need two moles of NaOH to
> react with one mole of H2SO4. The normality of a 1 mole per liter
> concentration of sulfuric acid is 2 N. The normality of a 1 mole
> per liter concentration of hydrochloric acid is 1 N.
>
> What type of hydrometer did you end up getting ?
>
> I think 1.245 is ok. My solution measures around 1.29
> I don't know the copper concentration, but going by the mass of
> copper dissolved during makeup and its final volume, its should
> be around 150 g/l.
>
>
> Adam