# Thread: Bleach Freezing Point & Consequences

1. ## Bleach Freezing Point & Consequences

What happens if Regular 6% Bleach freezes? I have about 20 gallons in 182 oz bottles out in the garage. Bringing them in is possible but I'd rather not but if it will lose it's CL I'll do it.

2. Hi jakebear and welcome to TFP!

....not to hijack your thread, but perhaps the responders could also include info on the freezing point of muriatic acid! I know there is a thread out here somewhere , just can't seem to find it!

Again, welcome.

Joyce

3. Taking the info from posts I made on The Pool Forum:

The freezing point depression of a 12% Sodium Hypochlorite solution (which also has 9.4% salt due to the manufacturing process of chlorine) is 15.3C or 27F so the freezing point is -15.3C or 5F. So unless you are expecting sustained temperatures well below freezing (i.e. closer to 5 degrees Fahrenheit or below), then it should be safe.

The full calculation was determined from the following. 12% solution is (approximately; ignoring Trade % vs. weight % distinctions) 12 grams of sodium hypochlorite in 100 grams total. There is also 12*58.443/74.4422 = 9.42 grams of salt (from the way chlorine is produced) so that's 100-12-9.42 = 78.58 grams water. There is 12/74.4422 = 0.1612 moles times 4 for dissociation and salt (there is sodium, hypochlorite, sodium, chloride) so 0.6448 moles solute in 78.58 grams water so in 1000 grams (1 kilogram) that is 8.2 so that times 1.86 is 15.3C = 27F.

The full calculation for bleach is determined from the following. 6% solution is (assuming weight %) is 6 grams of sodium hypochlorite in 100 grams total. There is also 6*58.443/74.4422 = 4.71 grams of salt (from the way chlorine is produced) so that's 100-6-4.71 = 89.29 grams water. There is 6/74.4422 = 0.0806 moles times 4 for dissociation and salt (there is sodium, hypochlorite, sodium, chloride) so 0.3224 moles solute in 82.29 grams water so in 1000 grams (1 kilogram) that is 3.92 so that times 1.86 is 7.3C = 13.1F.

[EDIT] For 8.25% bleach, this is 8.25 grams of sodium hypochlorite in 100 grams total. There is also 8.25*58.443/74.4422 = 6.48 grams of salt so that's 100-8.25-6.48 = 85.27 grams water. There is 8.25/74.4422 = 0.1108 moles times 4 for dissociation and salt so 0.4433 moles solute in 85.27 grams water so in 1000 grams (1 kilogram) that is 5.20 so that times 1.86 is 9.7C = 17.4F.

The freezing point depression for 6% Sodium Hypochlorite as found in Clorox Regular and most Ultra brands of bleach is 7.3C or 13.1F so the freezing point is -7.3C or 19F. [EDIT] The freezing point depression for 8.25% Sodium Hypochlorite as found in the new Clorox and other brand of bleach is 9.7C or 17.4F so the freezing point is -9.7C or 14.6F. [END-EDIT]

The freezing point of full-strength Muriatic Acid (31.45% Hydrochloric Acid) is -46C (-50.8F) (for Hasa; other brands quote even lower freezing points) so unless you live in the Artic, I think you are safe to leave your Muriatic Acid outside.

[EDIT] The freezing point of half-strength Muriatic Acid (say, 15% Hydrochloric Acid) is -18C (-0.4F). [END-EDIT]

Richard

4. Thank you Richard Most of us may not be able to follow the full "freezing point depression" causes, but with solid numbers, ie, 5F, it doesn't take an advanced degree to understand

Thanks again for all the info you provide

5. Thanks to all -- Guess I'll move it in when the temp drops

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