Yes, the exact amount of initial water for titration is not important. The
water is generally required so you have more solution volume to look at. 10
drops of solution would be difficult to see and properly mix, since if a
small bit splashed on the side of the glass it may not get mixed and give
false reading.
3 molar HCl is not too high. The only problem with high acid is fumes. If
HCl fumes are not a problem then you could of left it at 3 molar.
Concentrated HCl is about 12 molar.
http://www.howe.k12.ok.us/~jimaskew/cabconc.htmI found more copper is needed get get faster etching, I think the SG of my
solution was around 1.25 to 1.30 . Remember HCl is consumed during etching
so adding more copper means even less acid in your solution.
Stefan Trethan wrote:
> Hi all
>
> The new vertical tank is finally in use and i am pretty satisfied with the
> handling.
> it features a pcb clamp that can acceept all thicknesses, and this clap
> can be opened/closed
> with the same hand which also holds the lid/holder itself.
> I used a plastic rod which is spring loaded and pressed on with the thumb
> to open the clamp.
> this means i can feed the pcb and also afterwards drop it into the water
> tank without ever touching
> etchant-exposed parts or washing any part of the pcb holder.
> the visibility of the vertical glass tank is also great.
>
>
> But to my questions:
>
> With CuCl analysis, the initial amount of water does not play a major role
> i think?
> the instructions call for 5ml of water, then 10 drops of etchant, 1 drop
> of indicator,
> and then n drops of 1mol NaOH which are the etchant molarity∗10.
>
> Is it necessatry to measure this initial amount of water?
> Is it correct that the only important thing is the equal size of
> etchant/NaOH drops?
>
> I guess it would also be possible to make a "ready to use"
> water/methylorange solution?
>
>
> The molarity of the etchant i used in the old tank was over 3, so i
> diluted it with water
> to get 1.5. of course the etching is now terribly slow, because i have
> nearly no copper in.
> i will dissolve some copper to get the density up (the hygrometer is off
> range, 1.6 would be
> the lowest value)
>
> Next question is about rubber. i have used a piece of bicycle hose to make
> the spring action of
> the clamp. will it hold up inside the etchant tank? it is not immersed but
> exposed to the fumes all the
> time. any experiences?
>
> thanks
>
> ST
>
>
>
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