hydrometer for ammonia

rbrigham · May 12, 2015

hi

I need to make 5% ammonia solution but seem unable to find an ammonia hydrometer in England or anywhere else
I can find household ammonia that says its 7-10% but need some way of diluting it to 5% and checking it

can anybody recommend s way to do this

thanks

robin

london

Tom Taylor · May 12, 2015

I think that you can determine the new volume by multiplying the ration of the two concentrations by the volume needed. e.g., 7/5 x 100mL = 140mL of 5% equals 100mL of 7%. I'm guessing so you may want to check a first year chemistry text where this is covered. Of course you can always convers to moles and go from there.

Thomas

paul_c5x4 · May 12, 2015

First step is to find the specific gravity of ammonia in solution - A quick search turned up this: www.tannerind.com/PDF/green-aqua-amm.pdf

According to the table on page 2, a 5% solution should have an S.G. of 0.9790 @60°F

Gerald C Koch · May 12, 2015

Ammonia solution concentration is measured in degrees Baumé oBe. You need a hydrometer that measures oBe < 1.0. Then you can look up the value to get the percent concentration. Strong ammonia solution is ~25% ammonia gas.

rbrigham · May 12, 2015

Thanks for the replies

Ive found somebody local that will supply 10% so i'm sorted

robin

Photo Engineer · May 12, 2015

What do you want? weight / weight or weight / volume or volume / volume or volume / weight? These all differ.

The easiest are those with the same units, but just doing it on a numerical amount may give errors. So, 50 ml Ammonia 10% in 50 ml of water may be believed to give 100 ml of 5%, but with Ammonia, the volume change may cause an error. That is why you need a hydrometer to measure the exact concentration. It will specify units Be. for the units you use in makeup.

PE

jochen · May 13, 2015

Hello,
here some data for the density at 20° C:

% NH3 Density; ° Bé
g/cm³

2 0.9895 11.5
4 0.9811 11.7
6 0.9730 13.9
8 0.9651 15.1
10 0.9575 16.2
12 0.9501 17.3
14 0.9430 18.5
16 0.9362 19.5
18 0.9295 20.6
20 0.9229 21.7

Steve Goldstein · May 13, 2015

Jochen, the third column in your post seems peculiar. Since the specific gravity is close to 1, I'd expect the density to be around 1 g/cm³, not 10 times as much!

Hello,
here some data for the density at 20° C:

% NH3 Density; ° Bé
g/cm³

2 0.9895 11.5
4 0.9811 11.7
6 0.9730 13.9
8 0.9651 15.1
10 0.9575 16.2
12 0.9501 17.3
14 0.9430 18.5
16 0.9362 19.5
18 0.9295 20.6
20 0.9229 21.7

jochen · May 13, 2015

Hello Steve,
it is correct that solutions of ammonia in water have densities below 1 and they fall with increasing concentration. The last column (right) contains the degrees Baumé (11.5, 11.7....). The first (left) is the concentration in % (2,4,6,8...) and the middle the density (0.9895...). The density of 24 % is 0.9101 with 23.8° Bé and 26 % has 0.9040 with 24.9° Bé. Sorry that the format of my little table was automatically changed. For densities below 1 a special Baumé spindle is used. The data are from the German "Chemiker Kalender" from 1974.

Steve Goldstein · May 13, 2015

Hi Jochen,

Oops, I missed that the "° Bé" went with the "g/cm³" notation that wrapped onto the next line. Thank you for clarifying this.

Tom Taylor · May 13, 2015

Photo Engineer said:
What do you want? weight / weight or weight / volume or volume / volume or volume / weight? These all differ.

The easiest are those with the same units, but just doing it on a numerical amount may give errors. So, 50 ml Ammonia 10% in 50 ml of water may be believed to give 100 ml of 5%, but with Ammonia, the volume change may cause an error. That is why you need a hydrometer to measure the exact concentration. It will specify units Be. for the units you use in makeup.

PE

Yes. But I was talking about using a lower % concentration to put in a solution calling for a higher concentration by simply multiplying the two ratios by the volume of the higher concentration called for in the formula:

x = % solution of the higher concentration
y = % solution of the lower concentration
v = Volume of the higher concentration called for in the formula (say 100mL)

Hence x/y * 100mL = the volume of y to be used.

This may not be an exact replacement from using 100mL of x but it looks like it will be close. What do you think?

Thomas

Photo Engineer · May 13, 2015

Usually, density goes up with addition of a material to water, but with Ammonia and a few other chemicals, density goes down. See the previous posts for that information.

Therefore, the final result using your calculation may be off, but I could not even guess by how much nor even knowing the amount it is off, if that is critical to your needs.

PE

Gerald C Koch · May 13, 2015

Consult the following to convert degrees Baume to percent.

http://www.tannerind.com/PDF/green-aqua-amm.pdf

Chris Rico · Jun 7, 2020

Looking for some knowledge on measuring ammonia with a hydrometer. My percentages out between 32 percent and 35 percent ammonia solution I was reading some of the posts and quickly made a account to gain some knowledge on getting a accurate reading for refrigeration.

AgX · Jun 8, 2020

Photo Engineer said:
Usually, density goes up with addition of a material to water, but with Ammonia and a few other chemicals, density goes down. See the previous posts for that information.

That is why one likely would only come across hydrometers for SG > 1.
However there are hydrometers offerd for SG < 1 too, even for little money.

hydrometer for ammonia

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