# need help with hcl potentials?



## Geo (Jan 30, 2013)

could someone please tell me how much copper can be dissolved with a set amount of hcl. if i understand correctly, it should be 2 moles of hcl for 1 mole of copper. does this mean that 1 pound of 32% hcl will dissolve .5 pounds of copper? i really need this information for my notebook. i have several chemistry books and im sure it states it precisely but i cant understand all the equations. i really need someone to tell me how much hcl it takes for X amount of copper. i believe ive been wasting chemicals because without understanding these amounts, im left using enough im sure will dissolve what i need which could be 2X or 3X too much.


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## FrugalRefiner (Jan 30, 2013)

Geo,

Assuming the end product of your reaction between the HCl and copper is copper II chloride (CuCl2), then you are correct that you need 2 moles of HCl for 1 mole of copper. But the molecular weights of HCl and copper are different, so it's not a 1 pound to a half pound relationship.

One mole of HCl weighs 36.461 grams.

One mole of copper weighs 63.546 grams.

So you would need 72.922 grams of HCl to react with 63.546 grams of copper.

But the molecular weight of HCl is only the weight of the gas. Once it's dissolved in water, you need to combine the weight of 1 mole of HCl plus the water it is dissolved in.

The 32% HCl that we commonly use is 10.2 molar, meaning there are 10.2 moles of HCl in each liter of solution. So for 1 mole, divide 1000 ml by 10.2 moles. The result is that 98.04 ml of 32% HCl contains 1 mole of HCl.

The density of 32% HCl is 1.16. 98.04 ml times 1.16 grams per ml equals 113.73 grams. We need 2 moles, so 196.08 ml, or 227.46 grams.

So the final answer would be 196.08 ml (227.46 grams) of HCl would react with 63.546 grams of copper to form CuCl2.

I hope that makes some sense.

Dave


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## philddreamer (Jan 30, 2013)

Dave, so in other words, 1 galon of HCl in AP will dissolve 1pound 5.6 ounces of copper?
Thanks!
Phil


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## FrugalRefiner (Jan 30, 2013)

Oh sure, change all the units on me. :lol: 

1 gallon = 3.78 liters
3.78 liters * 10.2 moles per liter = 38.56 moles
38.56 moles HCl / 2 = 19.28 moles of copper
19.28 moles * 63.546 grams per mole = 1225.17 grams
1225.17 grams / 454 grams per pound = 2.7 pounds

Somebody please check my math. It's late.

Dave


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## modtheworld44 (Jan 30, 2013)

FrugalRefiner said:


> Oh sure, change all the units on me. :lol:
> 
> 1 gallon = 3.78 liters
> 3.78 liters * 10.2 moles per liter = 38.56 moles
> ...



FrugalRefiner

So how many ml's of hcl does it take for an ounce of mixxed pins?



modtheworld44


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## Geo (Jan 30, 2013)

dang Phil, we came up with two separate numbers. this is what i did.

(196/2=98) (63.5/2=31.7) (3785.4/98=38.6) (453.5/31.7=14.3) (38.6X14.3=1223.6) (1223.6/453.5=2.69)

2.69 pounds of copper. someone please check my math.


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## philddreamer (Jan 30, 2013)

I thought I had read some where that it was around 3 pounds of copper per galon of HCl, (or so), so 2.7 pounds sound good to me. 
I, like Geo, also discarded AP thinking that it was too saturated with copper, only to find out, when recovering the copper, that the solution was still "pretty hot"! Now I know better!
For the past month I've started re-using 20 galons of "spent" AP, and the AP it still dissolving plenty of copper. I also started cementing copper with steel dust from a dry steel band saw, and it's instant copper powder! 
Thanks!
Phil


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## philddreamer (Jan 31, 2013)

Dave wrote:


> So the final answer would be 196.08 ml (227.46 grams) of HCl would react with 63.546 grams of copper to form CuCl2.


Well, I just multiplied 64 fluid ounces x 29.57ml per ounce = 1,892.48ml per galon. Then divided 1,892.48ml by 196.08ml (of HCl needed per every 63.546g of Cu) = 9.65157
9.65157 x 63.546g = 613.3187g divide by 453.6g per Avo. pound = 1.352 pounds or 1 pound 5.63 ounces. 
But I really like the 2.7 pounds much better! :mrgreen: 
Phil


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## FrugalRefiner (Jan 31, 2013)

modtheworld44 said:


> FrugalRefiner
> 
> So how many ml's of hcl does it take for an ounce of mixxed pins?


modtheworld,

That is a much harder question to answer. It depends on what the pins are made of. Geo's question dealt with only copper and HCl. Pins can be made from many different materials from copper alloys like brass or bronze to iron alloys like Kovar. Unless you know the chemical composition of the pins, you can't really calculate an amount accurately.




philddreamer said:


> Well, I just multiplied 64 fluid ounces x 29.57ml per ounce = 1,892.48ml per galon. Then divided 1,892.48ml by 196.08ml (of HCl needed per every 63.546g of Cu) = 9.65157
> 9.65157 x 63.546g = 613.3187g divide by 453.6g per Avo. pound = 1.352 pounds or 1 pound 5.63 ounces.
> But I really like the 2.7 pounds much better!
> Phil


Phil,

There are 128 ounces in a gallon.

Now when it comes to the dynamics of AP and when it is "spent", I'll defer to Lazersteve's expertise. Remember there is a balancing act going on between CuCl and CuCl2. My answers above only apply when the end product is solely CuCl2. 

Dave


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## butcher (Jan 31, 2013)

HCl alone will not dissolve copper.

HCl + Cu --> no reaction
(copper cannot be oxidized, (or lose electrons) by the acid, to dissolve into solution, as copper is less a reactive than hydrogen in the reactivity series.

The copper needs to be oxidized first; we need H2O2, or a strong oxidizer to begin with, to oxidize some copper into solution, to convert the copper to an oxide in the acidic solution.
Then the copper oxide can be dissolved in the HCl acid forming copper chlorides.

Cu + H2O2 --> CuO + H2O 
(For this to react to any extent the solution would need to be acidic)

Cu + H2O2 + 2HCl --> CuCl2 + 2H2O
And
CuO + HCl --> CuCl + H
But with more HCl
CuO + 2HCl --> CuCl2 + H2O 

Now we do not need HCl in this acidic solution to dissolve more copper into solution.
Copper II chloride dissolves more copper into solution:

Cu +CuCl2 --> 2CuCl
(So we see our solution of CuCl can hold more copper here than it did as CuCl2)

This solution will contain both CuCl2 and CuCl as a very dark green, almost green brown solution before being saturated with CuCl and precipitating CuCl as a white powder, (temperature, acidity pH, concentration, can also play a big factor in how much copper is held in solution) 

Once solution is saturated with copper I chloride it will form a white copper I chloride precipitant, we can add a little HCl and oxygen to rejuvenate the solution:

2CuCl + 2HCl + O --> 2CuCl2 
Ready to dissolve more copper into solution


I do not think we can just calculate how much copper that can dissolve into solution with just using the formula 2HCl + Cu --> CuCl2 (actually this equation does not exist), or calculate how much copper is dissolved into solution just using the formula CuCl2 alone, as the solution could be a mix of CuCl and CuCl2, this solution can hold different amounts of copper depending on many factors pH, temperature, concentration and so on, we also see the HCl is not what dissolves copper into solution but actually the CuCl2 which dissolves more copper into solution, the other actions of water acid and oxidizers also come into play.

So with my very limited skills in figuring these chemical equations mathematically I feel it would be very hard to tell exactly how much HCl would dissolve or hold how much copper it would hold in this solution, and I would not even wish to try to figure it out, at least mathematically through chemical equations.

I have used my used copper chloride solution heated it strongly with copper metal and was very surprised at the pounds of copper this solution would dissolve and hold as it became syrupy (on cooling which would convert to copper I chloride salts) (or the amounts of other metals like iron it would dissolve).

I have used this to lower my waste solution volume, as a way of dealing with volumes of waste (if using copper powders previously cemented I can just dry these copper powders).

Or I can dissolve more copper for recovery process using the used solutions (but have to put the copper I powders back into solution if I allow them to form recovering values with this process, so I do not think it saves much acids or reagents, and then the waste solution is brought right back up in volume, so it has very limited gain or uses as a recovery method, (but can be used at times with manipulation of solution before letting solution cool or forming salts).

This can also be used to dissolve steel or iron based metals, by using the copper chloride waste to dissolve iron or steel from scrap forming iron chlorides (which actually helps to dissolve more copper, one thing with strong heating is you will also form insoluble iron hydroxides in mix as red rouge, dealing with these solutions, and recovery of values from the them would be hard to explain, but if you have a fairly good understanding of dealing with the troubles then it is not that hard figure out.

I would not try to calculate this out, but I love it when you guys try, it helps me learn more how it is done.


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## philddreamer (Jan 31, 2013)

> There are 128 ounces in a gallon.


AHAH! My bad...  

Well, at least I was half correct! :lol:


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## butcher (Jan 31, 2013)

Phil, 
I only say the half you got right, never did see the other half.


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## Geo (Jan 31, 2013)

thank you Butcher for the explanation. i understand how a new member would not understand my simplistic question about hcl. i probably should have explained my question a little better but i was thinking in simple terms and was hoping for a simple answer (thank you Dave).for those of us that are a little farther along in our studies would understand what i was getting at.i guess a better way to have phrased it would have been "how much copper can be held in suspension by 1 gallon of hcl?".

Butcher has a way of explaining things that even i can understand. 8)


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## lazersteve (Feb 1, 2013)

31% HCl is approximately 10 moles per liter (M).

There are 3.78 liters per gallon.

3.78 x 10 = 37.8 Moles per gallon of 31% HCl .

37.8 / 2 = 18.9 moles of copper from 37.8 moles of HCl in CuCl2

Copper weighs 63.55 grams per mole (g/M)

63.55g/M x 18.9 M = 1201.095 g

454 grams per pound (g/lb)

1201.095 g / 454 g/lb = *2.65 pounds of copper per gallon of 31% HCl *.

The above is close enough for government work. Figure a gallon per kilo.

Steve


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## solar_plasma (Nov 11, 2014)

butcher said:


> HCl alone will not dissolve copper.
> 
> 
> Once solution is saturated with copper I chloride it will form a white copper I chloride precipitant, we can add a little HCl and oxygen to rejuvenate the solution:
> ...



I think this step is incomplete. You surely meant:

4CuCl + 4HCl +O2 --> 4CuCl2 + 2H2O

Since the CuCl2/CuCl just works as a catalyst for letting the HCl dissolve the copper, in theory we have only to calculate the stoichiometry of Cu and HCl directly to CuCl2, in practice with an excess of HCl.


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## jungle_Dave (Feb 25, 2015)

Very interesting post, thanks for explaining this in detail as it was doing my head in as well.

I just have 1 suggestion though.
Why don't you guys just keep it metric? :lol:


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## Geo (Feb 25, 2015)

In the US, we use United States customary units which comes from the Imperial Units System. It's hard thinking in terms of metric when you grew up using a different standard. Our standard liquid measure that's used for almost every liquid sold in the US is the US gallon.


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## artart47 (Feb 25, 2015)

Hi friends!
If I'm not mistaken, I recall that the molar weight of a substance is the combined atomic weights of the atoms in a molecule???
Example; HCl. would be...(atomic weight of one hydrogen and one chlorine atom) expressed in grams. You would simply have to calculate how much of whatever percentage acid will contain one mole of HCl gas. If I'm in error, please fill me in. Hope that helped!

artart47


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## jungle_Dave (Feb 26, 2015)

Geo said:


> In the US, we use United States customary units which comes from the Imperial Units System. It's hard thinking in terms of metric when you grew up using a different standard. Our standard liquid measure that's used for almost every liquid sold in the US is the US gallon.



I get it Geo, spent quite a bit of time in the US myself, both systems have there advantages. Try to cut a cake in 10 pieces, its possible but not easy, the Imperial system has a clear advantage over metric there. Volume wise I just prefer metric. It's easier for "me" to count in 10's but hey, both work  

Best wishes,

Dave


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## MarcoP (Feb 26, 2015)

To me there is not any difference between imperial and metric, it all depends what did you grow up with and measuring tools you have on hand.


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## bswartzwelder (Feb 27, 2015)

MarcoP said:


> To me there is not any difference between imperial and metric, it all depends what did you grow up with and measuring tools you have on hand.


 
True, but when my wife and I visited Spain a couple of years ago, we were shocked at how cheap the gasoline prices were until we found out the prices shown were for liters and not gallons.


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## MarcoP (Feb 27, 2015)

bswartzwelder said:


> MarcoP said:
> 
> 
> > To me there is not any difference between imperial and metric, it all depends what did you grow up with and measuring tools you have on hand.
> ...


Read this witty reply by jason_recliner http://goldrefiningforum.com/phpBB3/viewtopic.php?f=33&t=21284#p219822


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