Sciencemadness Discussion Board

0.1M HCl questions

NEMO-Chemistry - 2-1-2018 at 09:43

I need to make up a stock solution of approx 200ml 0.1 HCl.

First question is a check of my maths....

Starting with 36.5% HCl
room temp and water temp around 5C

Roughly add 180ml DW to volumetric flask

Add 1.69ml of HCL to flask
Then top up to line with approx another 8.3ml DW

This should give me a approx 0.1M solution??

Storage.......

HCl is a bastard for rusting stuff, the bottle i need to store this in is a old glass lab bottle (ground glass), can i use a normal ground glass stopper or rubber bung to store this in? Or do i need to get creative to stop it escaping?

I am only needing it around for a week or so.

The Austrian Scientist - 2-1-2018 at 09:49

Yes, but to be precise you need to add 2 mL of conc. HCl.

Storage of the 0,1 M solution shouldn´t be a problem since the HCl is very dilute and not much HCl vapours are ecaping.

[Edited on 2-1-2018 by The Austrian Scientist]

ninhydric1 - 2-1-2018 at 10:40

As The Austrian Scientist said, it shouldn't be a problem. If you are really afraid that HCl gas could leak out, put some Teflon or electrical tape around the seam during storage. I do this if I'm storing concentrated (37%) HCl, or 2.0 M or higher.

NEMO-Chemistry - 2-1-2018 at 11:08

Thx guys
Shit my maths was off! Not that it matters for this, its only got to be 'about' 0.1M.

Sulaiman - 2-1-2018 at 11:13

The main unknown is the original HCl concentration,

you can titrate the original acid, or better, the dilluted product - e.g. vs. sodium carbonate
in theory (I've not tried) you could diute the HCl to about 20.2% w/w and boil it until a constant temperature is achieved - you should then be sure to have Azeotropic HCl

aga - 2-1-2018 at 11:21

I think the constant boiling point would be just water.

The bit boiling off at 108 C would be around 20% conc. HCl.

happyfooddance - 2-1-2018 at 11:23

I never use this, but https://www.sigmaaldrich.com/chemistry/stockroom-reagents/le...

JJay - 2-1-2018 at 11:26

Sulaiman is correct. You can actually know the concentration of the HCl very precisely if you know the barometric pressure.

The Austrian Scientist - 2-1-2018 at 11:40

For such calculations I got an app on my phone.

NEMO-Chemistry - 2-1-2018 at 11:52

I got a hydrometer?

I didnt think about getting an app on the tablet! In this case the numbers dont have to be ultra precise. I was more concerned I would be a decimal point off lol.

aga - 2-1-2018 at 12:13

Stick a measuring cylinder on some scales, tare them, then measure out 10ml and record the weight.

That'll give you the approximate density.

Wiki has a table https://en.wikipedia.org/wiki/Hydrochloric_acid that will give you an approximate w% based on that density.

It will probably be around 36 w% like it says on the bottle, although that kind of FUMING HCl concentration i have never seen available anywhere (max i got is 32 w%).

With a w% figure and density (and the m.w.) you can work out the [M] of your HCl, then use th C1V1 = C2V2 formula to work out how much water to add to get to your target concentration.

happyfooddance - 2-1-2018 at 12:16

http://www.handymath.com/cgi-bin/hcltble3.cgi?submit=Entry

unionised - 2-1-2018 at 12:18

Quote: Originally posted by NEMO-Chemistry  


Add 1.69ml of HCL to flask
Then top up to line with approx another 8.3ml DW


Strictly, you missed a bit

Add 1.69ml of HCl to flask

Wait for it to cool
Then top up to line with approx another 8.3ml DW

happyfooddance - 2-1-2018 at 13:11

Quote: Originally posted by unionised  
Quote: Originally posted by NEMO-Chemistry  


Add 1.69ml of HCL to flask
Then top up to line with approx another 8.3ml DW


Strictly, you missed a bit

Add 1.69ml of HCl to flask

Wait for it to cool
Then top up to line with approx another 8.3ml DW



Why would it need to cool unless he was adding dry HCl(g)?

NEMO-Chemistry - 2-1-2018 at 13:29

Quote: Originally posted by happyfooddance  
Quote: Originally posted by unionised  
Quote: Originally posted by NEMO-Chemistry  


Add 1.69ml of HCL to flask
Then top up to line with approx another 8.3ml DW


Strictly, you missed a bit

Add 1.69ml of HCl to flask

Wait for it to cool
Then top up to line with approx another 8.3ml DW



Why would it need to cool unless he was adding dry HCl(g)?


Because i took the temperature into consideration as it was a long way from normal room temp.

Unionised helps me by pointing out the little bits I miss. He isnt being pedantic, he is just aware I like to know all the wrinkles and details without a full blown analysis.

While this particular procedure didnt have to be spot on, i was trying to make sure I had the procedure right. I have some more to do later next week, those need to be more accurate.

I no longer own a measuring cylinder aga.... i need to rectify that, yet AGAIN!! Time to splash out on a couple of those bumper ring things :D.

The acid origanaly came from ACP Pure around 18 months ago, i brought 15 ltrs in 3 X 5ltr containers. This is a new one i just opened. Back when I got it, they were all marked 36.6%, but i notice on the site now they have put a range.

Mine however does have the analysis report on the label.

Not much help to you in spain but just in case
https://apcpure.com/product/hydrochloric_acid_35_0_36_6_acs_...

They have a new director and recently some of their practices have been a bit shoddy! They have two main Brands Atom Scientific and ACP Pure, both use exactly the same chems and both are from exactly the same building. But Atom Scientific is aimed at B2B and is double the price.

What annoys me is some chems like Chloroform they now only sell via Atom, its fairly cheap except. I placed an order for ACP pure over the phone, i then asked for some Chloroform.

Despite it being delivered by the same company on the same day, they wouldnt include the shipping cost as one order! so they wanted £45 for the ACP order (delivery) and another £45 for the Chloroform!! Despite the fact it would have been on the same van at the same time!! The ACP order also had 96% sulphuric acid in it amongst other Hazmat chems!

They have now lost a good customer! The shipping was more than the cost of 2.5ltr Chloroform.

I appreciate the input guys.

[Edited on 2-1-2018 by NEMO-Chemistry]

unionised - 2-1-2018 at 13:33

Quote: Originally posted by happyfooddance  
Quote: Originally posted by unionised  
Quote: Originally posted by NEMO-Chemistry  


Add 1.69ml of HCL to flask
Then top up to line with approx another 8.3ml DW


Strictly, you missed a bit

Add 1.69ml of HCl to flask

Wait for it to cool
Then top up to line with approx another 8.3ml DW



Why would it need to cool unless he was adding dry HCl(g)?


Because diluting concentrated HCl evolves heat.

Incidentally you can get a reasonable estimate of the density without a measuring cylinder.
Get a bottle and weigh it empty and then full of water- the difference gives you the volume.
If you then weigh it full of HCl solution (or whatever) you can find the weight of a known volume.
That lets you calculate the density.

[Edited on 2-1-18 by unionised]

happyfooddance - 2-1-2018 at 13:34

But why would you be pouring hot concentrated hydrochloric acid?

unionised - 2-1-2018 at 13:36

Quote: Originally posted by happyfooddance  
But why would you be pouring hot concentrated hydrochloric acid?

It doesn't need to be hot.
If you mix cold concentrated hydrochloric acid with water it gives out a little heat.

NEMO-Chemistry - 2-1-2018 at 13:38

Quote: Originally posted by happyfooddance  
But why would you be pouring hot concentrated hydrochloric acid?


see my post just above, it explains why and how he gave the info.

NEMO-Chemistry - 2-1-2018 at 13:39

Quote: Originally posted by unionised  
Quote: Originally posted by happyfooddance  
Quote: Originally posted by unionised  
Quote: Originally posted by NEMO-Chemistry  


Add 1.69ml of HCL to flask
Then top up to line with approx another 8.3ml DW


Strictly, you missed a bit

Add 1.69ml of HCl to flask

Wait for it to cool
Then top up to line with approx another 8.3ml DW



Why would it need to cool unless he was adding dry HCl(g)?


Because diluting concentrated HCl evolves heat.

Incidentally you can get a reasonable estimate of the density without a measuring cylinder.
Get a bottle and weigh it empty and then full of water- the difference gives you the volume.
If you then weigh it full of HCl solution (or whatever) you can find the weight of a known volume.
That lets you calculate the density.

[Edited on 2-1-18 by unionised]


I will get to use my hydrometers one day!!

happyfooddance - 2-1-2018 at 13:49

I see. But isn't that heat pretty negligible? I thought that the HCl in 32% is pretty much just as completely disassociated as it is in dilute solution. I have a habit of stirring everything with a thermometer, and I have never noticed a temperature change diluting HCl acid.

Then again, with his new hi-accuracy thermometer set, he might!

NEMO-Chemistry - 2-1-2018 at 14:10

Quote: Originally posted by happyfooddance  
I see. But isn't that heat pretty negligible? I thought that the HCl in 32% is pretty much just as completely disassociated as it is in dilute solution. I have a habit of stirring everything with a thermometer, and I have never noticed a temperature change diluting HCl acid.

Then again, with his new hi-accuracy thermometer set, he might!

lol I used to stir with a thermometer......until a blob suddenly dropped to the bottom of the flask :D.

I got a couple of more accurate thermometers than those others from ebay, the lines are really close together though.

aga - 2-1-2018 at 14:11

Quote: Originally posted by NEMO-Chemistry  
... Unionised helps me by pointing out the little bits I miss. He isnt being pedantic ...

His/her username is unionised not Unionised.

That's being pedantic ;)

Edit:

Yes, i know, a Capital observation, heigh ho.

[Edited on 2-1-2018 by aga]

NEMO-Chemistry - 2-1-2018 at 14:14

Quote: Originally posted by aga  
Quote: Originally posted by NEMO-Chemistry  
... Unionised helps me by pointing out the little bits I miss. He isnt being pedantic ...

His/her username is unionised not Unionised.

That's being pedantic ;)

Yes and No, most people really hate it when there name is written wrong. Funny in a way as most of us dont use our real names...

unionised - 2-1-2018 at 14:23

Quote: Originally posted by NEMO-Chemistry  

Yes and No, most people really hate it when there name is written wrong. Funny in a way as most of us dont use our real names...



Wrongly.

aga - 2-1-2018 at 14:25

Wrongly writted is most surely wrongly read.

NEMO-Chemistry - 2-1-2018 at 16:26

Touche
Now feck off :P