Freezing point for Sterile Water & 91% Alcohol??
10-18-2004, 07:03 PM
#1
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Freezing point for Sterile Water & 91% Alcohol??
For our techno/mathematics & engineering members:
A solution of :
2000 Ml .9% Sodium Chloride (sterile water)
14 oz. 91% Alcohol
I refilled a Ritchie Compass with this solution hoping it will not freeze. What is the freezing point of this solution??
A solution of :
2000 Ml .9% Sodium Chloride (sterile water)
14 oz. 91% Alcohol
I refilled a Ritchie Compass with this solution hoping it will not freeze. What is the freezing point of this solution??
10-18-2004, 07:30 PM
#2
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Re: Freezing point for Sterile Water & 91% Alcohol??
In all honesty, I wouldn't have used anything containing salt at all in my compass (the "Ringer's" solution you have is similar to saline..).
In fact, I thought the "correct" fluid to use was something like clear glycerine.
BUT, since you've asked, you must also provide to us the altitude at which you want the calculation done at (I assume sea level) and for ultimate accuracy, we will also need the barometric pressure at the time of the proposed calculation.
Before we go thru this, however, I would check with Ritchie and see what they recommend to pour into the compass.
In fact, I thought the "correct" fluid to use was something like clear glycerine.
BUT, since you've asked, you must also provide to us the altitude at which you want the calculation done at (I assume sea level) and for ultimate accuracy, we will also need the barometric pressure at the time of the proposed calculation.
Before we go thru this, however, I would check with Ritchie and see what they recommend to pour into the compass.
10-18-2004, 10:18 PM
#3
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Re: Freezing point for Sterile Water & 91% Alcohol??
1 mole of NaCl in a liter of water lowers the freezing point about 1.9*C.
In fact, 1 mole of just about anything dissolved in water will do the same. It does so by being "in the way" of the formation of the ice crystal structure.
At some concentration level, the water "becomes" the stuff dissolved in the other solution, assuming the other solution is indeed a homogeneous liquid...
For your purposes, we will look at the makeup of both components...
2000ml of 0.9% Ringers.
You got 1982ml water, and 18ml salt.
14oz 91% alcohol (about 420ml).
You got 37.8ml water, and 382.2ml alcohol.
One mole of salt (NaCl) = 27gm, or 28ml (according to the density chart).
One mole of alcohol (C2H6O) = 46gm, or 52.8ml (.87g/ml @-10C, it increases with lower temps since it is also a liquid).
So, we got 18ml of salt, which works out to 0.642 mole.
We got 382.2ml alcohol, which works out to 7.24 mole.
Add them together: you got 7.882 mole.
How much water? 1982ml + 37.8ml = 2.01 liter
7.882/2.01 = 3.92 moles of dissolved impurities per liter of water.
3.92 moles x 1.9*C = 7.45*C = 13.41*F depression in freezing point.
Therefore, your compass should freeze at 18.6 degrees F give or take a half a degree (assuming normal barometric pressure and sea level altitude).
Of course, this is just a guess...
In fact, 1 mole of just about anything dissolved in water will do the same. It does so by being "in the way" of the formation of the ice crystal structure.
At some concentration level, the water "becomes" the stuff dissolved in the other solution, assuming the other solution is indeed a homogeneous liquid...
For your purposes, we will look at the makeup of both components...
2000ml of 0.9% Ringers.
You got 1982ml water, and 18ml salt.
14oz 91% alcohol (about 420ml).
You got 37.8ml water, and 382.2ml alcohol.
One mole of salt (NaCl) = 27gm, or 28ml (according to the density chart).
One mole of alcohol (C2H6O) = 46gm, or 52.8ml (.87g/ml @-10C, it increases with lower temps since it is also a liquid).
So, we got 18ml of salt, which works out to 0.642 mole.
We got 382.2ml alcohol, which works out to 7.24 mole.
Add them together: you got 7.882 mole.
How much water? 1982ml + 37.8ml = 2.01 liter
7.882/2.01 = 3.92 moles of dissolved impurities per liter of water.
3.92 moles x 1.9*C = 7.45*C = 13.41*F depression in freezing point.
Therefore, your compass should freeze at 18.6 degrees F give or take a half a degree (assuming normal barometric pressure and sea level altitude).
Of course, this is just a guess...
Last edited by mcollinstn; 10-18-2004 at 10:23 PM.
10-18-2004, 10:42 PM
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Re: Freezing point for Sterile Water & 91% Alcohol??
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10-18-2004, 11:20 PM
#5
Re: Freezing point for Sterile Water & 91% Alcohol??
Originally Posted by mcollinstn
1 mole of NaCl in a liter of water lowers the freezing point about 1.9*C.
In fact, 1 mole of just about anything dissolved in water will do the same. It does so by being "in the way" of the formation of the ice crystal structure.
At some concentration level, the water "becomes" the stuff dissolved in the other solution, assuming the other solution is indeed a homogeneous liquid...
For your purposes, we will look at the makeup of both components...
2000ml of 0.9% Ringers.
You got 1982ml water, and 18ml salt.
14oz 91% alcohol (about 420ml).
You got 37.8ml water, and 382.2ml alcohol.
One mole of salt (NaCl) = 27gm, or 28ml (according to the density chart).
One mole of alcohol (C2H6O) = 46gm, or 52.8ml (.87g/ml @-10C, it increases with lower temps since it is also a liquid).
So, we got 18ml of salt, which works out to 0.642 mole.
We got 382.2ml alcohol, which works out to 7.24 mole.
Add them together: you got 7.882 mole.
How much water? 1982ml + 37.8ml = 2.01 liter
7.882/2.01 = 3.92 moles of dissolved impurities per liter of water.
3.92 moles x 1.9*C = 7.45*C = 13.41*F depression in freezing point.
Therefore, your compass should freeze at 18.6 degrees F give or take a half a degree (assuming normal barometric pressure and sea level altitude).
Of course, this is just a guess...
In fact, 1 mole of just about anything dissolved in water will do the same. It does so by being "in the way" of the formation of the ice crystal structure.
At some concentration level, the water "becomes" the stuff dissolved in the other solution, assuming the other solution is indeed a homogeneous liquid...
For your purposes, we will look at the makeup of both components...
2000ml of 0.9% Ringers.
You got 1982ml water, and 18ml salt.
14oz 91% alcohol (about 420ml).
You got 37.8ml water, and 382.2ml alcohol.
One mole of salt (NaCl) = 27gm, or 28ml (according to the density chart).
One mole of alcohol (C2H6O) = 46gm, or 52.8ml (.87g/ml @-10C, it increases with lower temps since it is also a liquid).
So, we got 18ml of salt, which works out to 0.642 mole.
We got 382.2ml alcohol, which works out to 7.24 mole.
Add them together: you got 7.882 mole.
How much water? 1982ml + 37.8ml = 2.01 liter
7.882/2.01 = 3.92 moles of dissolved impurities per liter of water.
3.92 moles x 1.9*C = 7.45*C = 13.41*F depression in freezing point.
Therefore, your compass should freeze at 18.6 degrees F give or take a half a degree (assuming normal barometric pressure and sea level altitude).
Of course, this is just a guess...
BTW -- Next time, just send it to Ritchie, and they will refurbish it. It is cheap and the compass comes back looking like brand new.
10-18-2004, 11:32 PM
#6
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Re: Freezing point for Sterile Water & 91% Alcohol??
Originally Posted by KaamaScarab30
You are scarily smart
Some people retain water, I retain math (and carbohydrates).
Gold Member
10-19-2004, 12:15 PM
#8
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Thread Starter
Re: Freezing point for Sterile Water & 91% Alcohol??
Damn!! That's amazing!! My hat is off to you.
I did not know that Ritchie would "refurbish" a compass. My compass "oil" had gotten so thick the disc would not rotate properly, so I removed the oil & put the water/alchol mix in as a test for the compass. It now follows correctly. I will now contact Ritchie about the refurb.. anybody got a web address??
Thanks Guys, I knew you would have the answer!!
I did not know that Ritchie would "refurbish" a compass. My compass "oil" had gotten so thick the disc would not rotate properly, so I removed the oil & put the water/alchol mix in as a test for the compass. It now follows correctly. I will now contact Ritchie about the refurb.. anybody got a web address??
Thanks Guys, I knew you would have the answer!!
10-21-2004, 07:09 PM
#10
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Posts: n/a
Re: Freezing point for Sterile Water & 91% Alcohol??
My buddy owns Maine Compass Service, there are a frightening number of cheap vodka bottles in the building. Vodka wors great for this application. if you have a vacuum pump, you can pump the air out and remove the bubbles and fill the chamber entirely.
Dave
Dave
