Chlorine/Sodium Hypochlorite

Discussion in 'Chemistry' started by Radelaide, Mar 19, 2013.

  1. Radelaide Registered Member

    We recently had an issue in my work place where a water cooler jug contained water with high readings of chlorine (50ppm), there's no foul play suspected, and its been determined that the water jug had residue from the chlorine-based product used to disinfect the water prior to it being refilled.

    Anyway, I have to questions, which I have not been able to determine.

    1) Someone in our office, who uses the water from the cooler on a regular basis to make his coffee believes that if he had used this water with such a high level of chlorine, that it would have produced Chlorine Gas after being heated up in the coffee maker. Is that possible? Although this may be a taboo question, I thought that it would not be as simple as heating heavily chlorinated water.

    2) Does chlorine sink or rise in water?

    3) I know this is junk science, but someone decided to test the water with their swimming pool strips, and took a sample of the water home with them on a hot summers day, and tested it about 24 hours later. The bottle was sealed the entire time. How would that effect how the chlorine dissolved, if any?

    3a) also the person said that they determined that the water was over 50ppm, as when they tested the water from the cooler, they diluted 2ml of that water (with chlorine) with 18ml of non-chlorinated water, which when tested with the pool strips (which only provide a reading of up to 10ppm), produced a reading of 5ppm, thus, he says that this determined that the water in the cooler was over 50ppm. Junk science, or sound theory?

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  3. arauca Banned Banned

    1) Assuming they use bleach NaOCl then the bleach is diluted with large amount of water, so the will be HOCl which is not stable , and it will decompose into Cl2 which is a gas , this in term will react with some surface as a electron donor, and if the pot is open some or large part will be released into the environment As a whole I see there will be a negligible amount left.
    2) Chlorine is a gas and heated will rise
    3) It depend on the container in which it was sealed . if it was a plastic water bottle the gas could have permeated through the wall or it could react with the containers wall.
    3a) How did the know the 18 ml water was Chlorine free , was it tap water ? or analyzed Chlorine free. I understand it was expected to have a lower ppm . But this could be a problem , the so called Chlorine free water . To my understanding Tap water is Chlorinated . If you have a true Chlorine free water then you probable are right .
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  5. exchemist Valued Senior Member

    One qualification to this: chlorine dissolves fairly well in water: Wikipaedia says ~3g/l @ NTP. As a mass fraction this would be 3000 ppm. So it seems easily possible that 50ppm could be left behind after a sterilisation operation with hypochlorite.

    Regarding the amount of free Cl left in normally chlorinated tap water, I found some data on the web (from Canada) indicating that the max permitted level is usually in the order of 1mg/l i.e. 1 ppm (mass basis). Such a low level would not account for the concentration observed in this case.

    Re heating water containing dissolved Cl, it is indeed true that the solubility of a gas in a liquid decreases as the temperature rises. So Cl₂ would be evolved if a solution of Cl were to be heated. You might smell it, but it would be unlikely to do you any damage in these quantities, I think.
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  7. KitemanSA Registered Senior Member

    Chlorine is a HEAVY gas and will typically sink
  8. exchemist Valued Senior Member

    11,200 air, yes, of course. Cl₂ is a lot heavier than N₂ or O₂.

    But the question was about whether it would sink or rise in water.

    In water, it will either dissolve or bubble up to the surface.
  9. Captain Kremmen All aboard, me Hearties! Valued Senior Member

    It's very unlikely that very dilute bleach would cause a problem.
    For the same reason that the water in a chlorinated swimming pool doesn't cause problems.
    Chlorinated water tastes ferkin' awful.

    I remember from my very early days,
    when my father drank from a lemonade bottle that my mother thought was just perfect for household bleach.
    A drop of household bleach was strong stuff. It would turn your clothes white at the point of contact.
    I don't know how much he drank, but he survived, and the episode became a family joke.
    We are made of stern stuff, we Kremmens.
    Last edited: Mar 21, 2013
  10. Nasor Valued Senior Member

    One of the "nice" things about chlorine is that it's very irritating and will usually become intolerable and drive people from the area before it becomes very dangerous.

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