LAU 發問於 科學及數學化學 · 9 年前

Hand-warmer!!!

Why sodium hydroxide not used as hand-warmer?

4 個解答

評分
  • 9 年前
    最愛解答

    Sodium hydroxide in solid or solution cannot give out heat. Only when we add water to it, the dilution will be exothermic so that heat will be given out. We cannot prepare sodium hydroxide solution already to expect it keeps on giving out heat because the exothermic reaction will end before we use it. On the other hand, we mustn't add water to solid sodium hydroxide to provide heat. Because it is highly corrosive and if you put in a plastic holder, it will corrode plastic too. So it would be a bad choice to use Sodium hydroxide as hand-warmer. And you should not do so.

    資料來源: Chem
  • 9 年前

    002: Gland. spell it.

    Also, how about a small, breakable container of water inside hand warmer? Like how one contains hydrogen peroxide in (chemiluminescent) light sticks played in Mid Autumn Fest.

    2012-04-28 15:04:31 補充:

    Also, avoid PUTTING EVERYTHING IN CAP!

    This is considered as shouting, which is inappropriate unless you're emphasizing something important. Even so, capitalizing a few lines is still to many.

  • 9 年前

    IN THIS CASE, NaOH IS IN SOLUTION AND IT WILL CARRY ON REACTION, SUCH THAT IT WILL GIVE OUT HEAT!

    1.NaOH(sodium hydroxide)is a alkaline, it is labelled as corrosive or irritant,so it is not suitable to contact with skin,eyesand any part of body

    2.we will have some sweat secrect by galinds(wrong spelling?) ,when sweats contact with NaOH ,duilution of alkaline is occur,i guess you know that dilution of acid and alkaline(or we call :base)will give out a lot of heat ,the heat even can turn the water added to become vapour, so duilution is very dangerous.IT MAY BURN YOUR HANDS!!!!!

    IF YOU DO NOT WANT YOU SKIN CONTACT WITH NaOH,THE BACKAGE SHOULD MADEBY PLASTIC OR OTHER SUBSTANCE THAT NaOH WILL NOT COME OUT FROM THE BACKAGE,BUT WHEN NaOH CANNOT COME OUT, YOUR SWEAT CANNOT GO INTO BACKAGE AND DUILUTE NaOH, THEN NO HEAT WILL BE GENERATE

    FINALLY, HOW HaOH WARM YOUR HANDS?SO NaOH CANNOT USED TO BE A HAND WARMER.

  • ?
    Lv 7
    9 年前

    Because when it mixes with water , the reaction give out lot of heat . It is a very vigorous reaction , hard to control in a pack of hand-warmer , moreover the reaction will go out very rapidly , soon all the heat gone . This hand-warmer will raise the temperature very high but last shortly . Plus NaOH is very corosive material , consider all these , it is not suitable to be used in Hand-Warmer .

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