1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Very Simple Question.

  1. Apr 24, 2007 #1
    Name the element which reacts most violently with Chlorine.

    My answer: Francium

    Please tell me if I am right or wrong?

    Thanks a lot in advance! :redface:
  2. jcsd
  3. Apr 24, 2007 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    I would tend to agree with you based on the electronegativity scale. A nagging question is, "What is meant by 'most violently'?" Most heat produced? Quickest reaction? It seems to me that chlorine (gas) reacting with a solid will be limited in its rate (violence?) by the surface area of the solid. A gas can be made to react almost instantaneously with another gas, so my choice for 'violence' would be hydrogen + chlorine.

    See here:

    http://jchemed.chem.wisc.edu/jcesoft/cca/CCA1/R1MAIN/CD1R1380.HTM [Broken]
    Last edited by a moderator: May 2, 2017
  4. Apr 24, 2007 #3
    Well, I agree, but violence here, I think would be rated in the terms of energy liberated. So does my answer fits with this definition of violence?
    Last edited by a moderator: May 2, 2017
  5. Apr 24, 2007 #4


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Your answer is fairly close. The most electropositive stable element is Cesium, however. The longest lived radioisotope of Francium has a half life of 21.8 minutes. At any given time on the crust of earth, there exists less than an ounce of Francium. No weighable quantity of Francium has ever been prepared or isolated on Earth. Its ionization energy is actually slightly higher than that for Cesium which implies that it is slightly less electropositive than Cesium. All of its chemical properties have been derived from radiochemical methods so the accuracy of these values might not be as high as for more stable elements.
  6. Apr 24, 2007 #5
    Define violent.

    I would guess Francium though aswell.
  7. May 9, 2007 #6
    Neutralizing Chlorine that has poisoned the ground

    In regards to Neutralizing Chlorine, if liquid chlorine has been spilled into the ground, is there any way to neutralize it that will not hurt or add any additional trauma to plants and/or animals?

  8. May 9, 2007 #7
    Chemistree is correct, that there is no practical way to react a sizeable quantity of Francium with Chlorine. Theoretically Francium SHOULD produce a more 'violent' reaction, as most texts I've seen state that "the lowest 1st ionization energy in the alkali metals is Francium". However, every reputable source that gives an ACTUAL ionization energy shows Cesium as slightly lower: (375.7 kJ Mol-1 vs Francium's 380 kJ Mol-1)
    Since most sources list Fr and Cs as having equal electronegativity, I would tend to agree that Cesium would actually react more violently with chlorine (although this goes against periodic trend).

    (and just so people don't ask, We can ignore differences in electron affinity becuase the Alkali metal is giving up its electron, not gaining one)

    as for the totally off topic hijack question of "neutralizing" chlorine, I havn't looked anything up but off the top of my head I'd say Magnesium or Calcium, they're far less dangerous on their own than Alkali metals, each mole of them will theoretically bond with two moles of chlorine, and both products Magnesium Chloride and Calcium Chloride are harmless salts. But for all practical purposes, you're probably better off just heavily dilluting the area with water.
  9. May 9, 2007 #8
    Offtopic Answer

    Most chlorine scrubbers consist of an aqueous NaOH solution. The chlorine dissolves in the solution and you get hypochlorite (bleach).

    Chlorine has a boiling point of around -34 deg C so unless you tipped over a dewar in the arctic it will vaporize. Due to the density of chlorine (and volume of gas if it was initially a liquid) the chlorine gas will probably lurk around for a little while but eventually go away, and if I were you I'd get far far away while that happens.
  10. May 9, 2007 #9


    User Avatar

    Staff: Mentor

    As Tim09 said - define violent.

    I will add one thing here. The faster the reaction, the more violent it is (most likely, may depend on the 'violent' definition). The more atoms of metal at the surface, the faster the reaction is. But there is less francium atoms per surface unit then cesium atoms - so if there are no other differences (electronegativity, electron affinity/ionisation), cesium reaction can be faster!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook