Conductivity of solutions

  1. hey im doin a chemistry assignment and i cant figure out how to do the following things

    Account for the difference in the conductivity of

    1.)sucrose solution and silver nitrate solution


    2.) solid silver nitrate and solid sodium metal


    3.) liquid (fused) sucrose and liquid(fused)silver nitrate

    please help
     
  2. jcsd
  3. cristo

    cristo 8,407
    Staff Emeritus
    Science Advisor

    Hi, and welcome to PF! Please note that our rules on homework help state that we cannot give out solutions before you have shown us your effort. Please post your thoughts on the question. Also, in future, please post in the other sciences section of the homework forum!
     
    Last edited: Jan 13, 2007
  4. sorry i well do so
     
  5. well for the first one i was thinking the difference would be because sucrose solution is molecular and insolube in water the conductivity is really low, and the conductivity of the silver nitrate in solution is very good because it is ionic and ionic bonded compounds generally have better conductivity? am i right? and if not whats wrong?
     
  6. for the second one, the AgNO3 would not conduct because of an ionic compound in the solid state, and the sodium metal conducts well because if not all most mettcalic compound always conduct.
     
  7. for the third one the ligquid solution of AgNO3 would be just as good as the solution of AgNO3 but i do not have ne ideas on the liquid silver nitrate
     
  8. cristo

    cristo 8,407
    Staff Emeritus
    Science Advisor

    Sucrose is soluble in water
    This is correct. Do you know why ionic solutions are more conductive?
     
  9. cristo

    cristo 8,407
    Staff Emeritus
    Science Advisor

    Correct. Do you know which specific properties of metals enable them to be good conductors?
     
  10. because the ions are free to move around in the water
     
  11. becuase in the a metal the electrons are not attcher to any particular cation and so theres a larger amount of mobile electrons?
     
  12. cristo

    cristo 8,407
    Staff Emeritus
    Science Advisor

    Read what you've put here again. I think the last bit should read but i do not have any ideas on the liquid sucrose.

    You're right with the AgNO3; the fused ions move and therefore the liquid conducts. For the sucrose, what has changed? Is the liquid sucrose molecular or ionic?
     
  13. nothing has changed, its still molecular, so it still doesnt conduct
     
  14. cristo

    cristo 8,407
    Staff Emeritus
    Science Advisor

    Well, the ions are free to move around in the solution.

    Correct. Metallic bonding is usually described as having a "sea of free electrons" enabling the metal to conduct.

    Correct
     
  15. im sorry to keep asking questions but i am strugglin in this class...

    i have to draw the cooling curves of both a pure solvent and solution.
    which one is correct


    PS
    -
    -
    -
    - ---------
    - -
    --

    solution

    -
    -
    - -----------
    - -
    --


    or

    PS
    -
    -
    -
    -
    -----------
    -
    -
    -
    and solution is the same but the flat line has a slight negative slope??
     
  16. cristo

    cristo 8,407
    Staff Emeritus
    Science Advisor

    Strictly, as you say, a pure solution would undergo a stage of "supercooling" in which the temperature drops below the freezing point, and then parabolically increases back to the freezing point, and levels out.

    Other than that, the graphs look fine.
     
  17. so is ut rge pciture on the website or the wordsi wrote
     
  18. cristo

    cristo 8,407
    Staff Emeritus
    Science Advisor

    You can add the parabolic part onto the graph on the website, so in answer to your question... both!

    It really depends how advanced your class is, but since you mentioned the "supercooling" then you should draw it on.
     
  19. alright thanks a bunch!!
     
  20. cristo

    cristo 8,407
    Staff Emeritus
    Science Advisor

    You're very welcome!
     
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