Conductivity of solutions
Question:
Why do some solutions conduct electricity, but other
don't? 
To answer the above question  we should learn more
about substances. We can divide substances in two different types: Electrolytes
and Nonelectrolytes. 
 

To learn more about this please visit this simulation:

https://phet.colorado.edu/en/simulation/legacy/sugar-and-salt-solutions
Rami, the laboratory assistant at the school Lab, prepared two different solutions for students:
1) He dissolved table salt, NaCl(s), with water.
2) He dissolved sugar C12H22O11(s) with water.
I recommend you to watch this video for
better understanding: 
https://www.youtube.com/watch?v=fwjvwoFHTbg

But Rami forgot to write the name of each solution at the beaker.
One student called Amir claimed that he can figure out each solution by checking the conductivity of it. 
Which statement is right?
 



1 People tried to answer this question

Amir is right, he can figure out the solutions because the lightbulb of the table salt solution will light up since the solution contains free electrons that behave as electrically conductive medium.

Amir is wrong he can't figure out the solutions because the light bulb of both solutions will light up.

Amir is right, he can figure out the solutions because the light bulb of
the table salt solution will light up since the solution contains free ions
that behave as electrically conductive medium.


Amir is right, he can figure out the solutions because the light bulb of the sugar solution will light up since the solution contains free ions that behave as electrically conductive medium.






Comments:
1.  kablan farida (2011-12-20 15:00:00)
Feedback

Hi Hiba,

Your question is very good, it was presented properly.
I like the simulation it is very useful, and it helped me to answer the question correctly.

I think that you wrote a great question which is understanding and analysis question, which is suitable for the middle school syllabus.

You should add information at the beginning of the question which will be useful, you can describe the structure of ionic substance.

 

Your point on map is very interesting and related to the topic.

 

Good Luck,

Farida

 

More information about Ionic conductivity:

Ionic conduction  is the movement of an ion from one site to another through defects in the crystal lattice of a solid or aqueous solution.

Ionic conduction is one mechanism of current. In solids, ions typically occupy fixed positions in the crystal lattice and do not move. However, ionic conduction can occur, especially as the temperature increases.

Ionic conduction is one of the mechanisms by which microwave ovens are believed to work. Microwaves cause ions dissolved in the microwaved sample to oscillate, colliding with neighboring molecules or atoms. These collisions cause agitation, motion or heat. This mechanism is important when considering the heating behavior of ionic liquids within a microwave.

Ionic conduction in solids has been a subject of interest since the beginning of the 19th century. Michael Faraday established in 1839 that the laws of electrolysis are also obeyed in ionic solids like lead(II) fluoride (PbF2) and silver sulfide (Ag2S).

 

2.  kablan farida (2014-12-20 15:00:00)
more information

3.  shehadeh marlene (2014-12-20 15:00:00)
question evaluation
Hi Hiba,
i liked the questions , it is suitable for the material and level of middle school students .

there are a few points to improve :
1- i think the simulation should be inside the question and not the answer , so it would not imply that this is the correct answer . 
the simulation itself is very helpful in understanding the material 

2- the point on the map should contain more details and pictures or a video clip. it is a wonderful topic and relates closely to the subject of the question

3- i think you can add a short video of the experiment or even other simple applications of this subject that can be done in the home kitchen , demonstrations are always a good way to learn.

4.  Taballag Hiba (2006-01-20 16:00:00)
Reply for Farida and Marlene:

Hi Farida and Marlene;

I really appreciate your efforts to write these useful comments; it helped me to improve my question.  I put the simulation inside the question itself and not at the answers according to your suggestion, Marlene, so it would not imply that this is the correct answer.I also added a video to the point on the map

I added a table which contains information about electrolytes and nonelectrolytes substances at the beginning of the question according to your suggestion, Farida.On purpose I didn't add a description to the structure of
ionic substance to encourage the students to visit the simulation and learn about the difference between ionic and molecular
compounds.
Good luck for you too. 

Hiba Taballag.















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