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Topic: How to find concentration  (Read 19976 times)

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Offline Trizocy

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How to find concentration
« on: February 09, 2015, 05:21:36 AM »
Hey

Looking for some help, are new to chemi so need help to find concentration.

I want to know how it works, so i got 1L bottle of Ammonia, on the description it stand 25%

How do you calculate it to 25%?
Tryed the destiny method but did not work.

Had a beaker with 50ml weight 44,65g.


Anyone can help me out :)?

Thanks

Offline Borek

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Re: How to find concentration
« Reply #1 on: February 09, 2015, 06:41:06 AM »
How do you calculate it to 25%?

You don't, it is given. Someone else checked what the concentration is.

Quote
Tryed the destiny method but did not work.

Please elaborate, no idea what you mean.
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Offline Trizocy

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Re: How to find concentration
« Reply #2 on: February 09, 2015, 06:54:15 AM »
Okay, forget about the density method  :P

Anyway, if i got 1L of ammonia and dont know what % of ammonia is in it, how do i calculate how much % is it?


Offline Borek

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Re: How to find concentration
« Reply #3 on: February 09, 2015, 09:39:30 AM »
You don't calculate the concentration - you determine it experimentally.

Calculation is part of the procedure but without some kind of measurement you can't do anything.
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Offline Trizocy

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Re: How to find concentration
« Reply #4 on: February 09, 2015, 10:49:25 AM »
What kind of measurement do you mean then?

All i want to know is how much ammonia (NH3) there is in the 1L bottle.


Offline Borek

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Re: How to find concentration
« Reply #5 on: February 09, 2015, 01:36:43 PM »
Anyway, if i got 1L of ammonia and dont know what % of ammonia is in it, how do i calculate how much % is it?

All i want to know is how much ammonia (NH3) there is in the 1L bottle.

Previously you have stated you don't know the concentration. If you don't know the concentration you can't pull it out of a thin air by some magical "calculations".

Chances are your question is "how much ammonia is in 1 L bottle of 25% solution", but so far you have failed to ask it. Instead you have mentioned

the destiny method

perhaps meaning "I know the density, which is necessary to calculate mass of the solution", but I can only guess.

Sorry, you have to be precise about what you know and what you are looking for. I don't see this thread arriving at any destiny with that density of mistakes.
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Offline Trizocy

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Re: How to find concentration
« Reply #6 on: February 09, 2015, 03:15:34 PM »
Hey Borek,

Sorry, my English is not the best, and are relative new in the chemical stuff. I will try to be more precise this time   :)

Okay, i saw a youtube video where some guy was concentrating Nitric acid, and when he was done concentrating, he put 0,6ml of the Nitric acid into a glass cylinder which gave 0,902 g. And the density of 100% Nitric acid is 1,51grams per ml, so here is the density method i call:

0,902g * 0,6ml = 1,503

1.503 / 1.51 * 100 = 99.54%



So yeah, the Nitric acid was 99%, okay then i wanted to try this method on my 1L ammonia bottle

100% Ammonia = 0.86 density (according to wiki)

So i put 50ml into a breaker, which gave 44,65g

Calculation:

0,4465g * 0,5ml = 0,22325g

0.22325 / 0.86 * 100 = 25.96% Ammonia

PS: hmm while i wrote this reply, it seems like the calculation was right this time, because the description on the bottle says 25% and my result is 25,96%
Anyway, is this a correct and good way to find the %?


If this is wrong again, please help me out  :-\ (Hope you get my point this time Borek ;) )
« Last Edit: February 09, 2015, 03:35:40 PM by Trizocy »

Offline Trizocy

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Re: How to find concentration
« Reply #7 on: February 09, 2015, 03:33:43 PM »
Okay, since the ammonia calculation did right, then i wanted to try a 1L bottle of Isopropyl alcohol (on the description it stand 99% 2-propanol)


100% density of Isopropyl alcohol is 0.786 g per ml.

So i put 5ml in a beaker and weight it, and gave me 38,45g

0,3845g * 0,5ml = 0,19225

0.19225 / 0.786 * 100 = 24.46% of 2-propanol in the 1L bottle  ???


Wrong? ,then i tryed to divide instead of multiply:

0,3845g / 0,5ml = 0,769

0.769 / 0.786 * 100 = 97.84% This time, it seems was much better, but why divide on this and not multiply? and is this right calculation?



Gonna try this calculation on a plumber-cleaning bottle (contain 60-90% sulfuric acid)

I am happy to know if anyone can confirm this method :)




Offline Borek

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Re: How to find concentration
« Reply #8 on: February 09, 2015, 04:04:14 PM »
I am not going to comment on "what some guy on youtube did" not seeing the video, but what you listed doesn't make much sense.

100% Ammonia = 0.86 density (according to wiki)

What units? It is the density of a liquid ammonia, or of a gaseous ammonia? If of a liquid ammonia - is it the same as ammonia solution, or is it something completely different?

Quote
So i put 50ml into a breaker, which gave 44,65g

OK, so you did an experimental measurement, that's good.

Quote
Calculation:

0,4465g * 0,5ml = 0,22325g

You can't multiply grams per mL and get grams.

Quote
0.22325 / 0.86 * 100 = 25.96% Ammonia

Sorry, but this is a random number, not even closely related to what you are trying to find.

The only way to check the solution concentration from your measurement is to calculate the density (you have both mass and volume), and find the related concentration in the density tables.
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Offline Borek

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Re: How to find concentration
« Reply #9 on: February 09, 2015, 04:05:16 PM »
I am happy to know if anyone can confirm this method :)

No, its is wrong.
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Offline Trizocy

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Re: How to find concentration
« Reply #10 on: February 09, 2015, 04:35:41 PM »
Hey Borek  ;D

Quote
Quote
Quote from: Trizocy on Today at 09:15:34 AM
100% Ammonia = 0.86 density (according to wiki)
What units? It is the density of a liquid ammonia, or of a gaseous ammonia? If of a liquid ammonia - is it the same as ammonia solution, or is it something completely different?

Well, i look up at wikipedia and there is stand: Density 1.84 g/cm3, liquid form. yeah and its the same as ammonia solution



Quote
Quote
Quote
Calculation:

0,4465g * 0,5ml = 0,22325g

You can't multiply grams per mL and get grams.

Haha, did not mean gram, but density  ;) thanks for correcting me


Quote
Quote
Quote
0.22325 / 0.86 * 100 = 25.96% Ammonia

Sorry, but this is a random number, not even closely related to what you are trying to find.

The only way to check the solution concentration from your measurement is to calculate the density (you have both mass and volume), and find the related concentration in the density tables.

Okay can you try to help me to find the solution concentration? have aldready write the mass and volume, do you need to know anything more?

Thanks  ;)

Offline Trizocy

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Re: How to find concentration
« Reply #11 on: February 09, 2015, 04:44:12 PM »
Hehe tryed the sulfuric acid also, but the number was 105% (60%-100%) so think my calculation is completely wrong  ;D ;D

Can someone help me out

Offline Borek

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Re: How to find concentration
« Reply #12 on: February 09, 2015, 06:08:05 PM »
Well, i look up at wikipedia and there is stand: Density 1.84 g/cm3, liquid form.

No, it doesn't say that. 1.84 g/mL looks more like the density of the pure sulfuric acid. But these densities are of no use here. Mostly because

Quote
and its the same as ammonia solution

ammonia solution and liquid ammonia are two different things.

Quote
Quote
The only way to check the solution concentration from your measurement is to calculate the density (you have both mass and volume), and find the related concentration in the density tables.

Okay can you try to help me to find the solution concentration? have aldready write the mass and volume, do you need to know anything more?

Which part of what I told you to do is unclear?
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Offline Trizocy

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Re: How to find concentration
« Reply #13 on: February 09, 2015, 06:49:32 PM »
Hey Borek

Quote
Quote
Well, i look up at wikipedia and there is stand: Density 1.84 g/cm3, liquid form.

No, it doesn't say that. 1.84 g/mL looks more like the density of the pure sulfuric acid. But these densities are of no use here. Mostly because

Yeah you had right sorry, had 3 wiki pages up, two of them was ammonia and sulfuric acid, so must have exchanged them  ;)


Quote
Quote
and its the same as ammonia solution

ammonia solution and liquid ammonia are two different things.

Did some lookup on the product, and on a pdf file does it stand it contains 25% ammonia solution


Quote
Quote
Quote
Quote
The only way to check the solution concentration from your measurement is to calculate the density (you have both mass and volume), and find the related concentration in the density tables.

Okay can you try to help me to find the solution concentration? have aldready write the mass and volume, do you need to know anything more?

Which part of what I told you to do is unclear?

I think the whole part was unclear, could you give me an example?

Offline Borek

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Re: How to find concentration
« Reply #14 on: February 10, 2015, 03:12:33 AM »
Quote
ammonia solution and liquid ammonia are two different things.

Did some lookup on the product, and on a pdf file does it stand it contains 25% ammonia solution

It still doesn't mean liquid ammonia and ammonia solution are the same thing. Liquid ammonia is a liquefied gas, ammonia solution is the ammonia dissolved in water. Completely unrelated concepts.

Quote
I think the whole part was unclear, could you give me an example?

Imagine you have weighed 100 mL of the ammonia solution, and it turned out its weight is 95.91 g. That means the density is 95.91 g/ 100 mL = 0.9591 g/mL

Google for an ammonia solution density table:

http://www.scribd.com/doc/30212886/Aqua-Ammonia-Specific-Gravity-Chart#scribd

There is no 0.9591 g/mL on the list, but it is apparently between 0.9605 g/mL (9.83%) and 0.9589 g/mL (10.28%). Your solution is more or less 10%.
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