How to test if some unknowns are covalent or ionic?

[IB]

So...how do you carry out an experiment to test if some unknowns are covalent (polar or non-polar) or ionic?

Unknowns:
C6H12O6 --NaCl --CH4N20 --C6H8O7

 

[mrjeffy321]

One way would be to dissolve them in water. Ionic compounds will break into ions and allow the solution to conduct an electric current, whereas covalently bonded substances will not.

Another way would be to find the substance's melting point. Ionically bonded compounds have much higher melting points.

 

[IB]

One way would be to dissolve them in water. Ionic compounds will break into ions and allow the solution to conduct an electric current, whereas covalently bonded substances will not.
Another way would be to find the substance's melting point. Ionically bonded compounds have much higher melting points.

What quantitative data can I gain from an experiment involving conductivity?

And by the way, how do you know which one is polar covalent which one is non-polar covalent? How would you perform an experiment to test that?

Thanks for your help, by the way! :)

 

[mrjeffy321]

What quantitative data can I gain from an experiment involving conductivity?

Testing the conductivity of the solution will let you know, yes/no the substance breaks into ionx in solution (ionic). If the solution is indeed conductive, then perhaps you can measure the amount of resistance [ohms] between the electrodes.
I can however think of an example which might make this test less valuble to you. HCl, Hydrogen chloride gas is covalently bonded, but when you dissolve it in water, the solution will conduct electricity.


Tesing if the substance if polar/non polar covalently bonded is harder. One way of experimentally finding this might be to use the "like dissolves like" dissolving rule. Polar solvents dissolve polar solutes (this includes ionic bonds and polar-covalent bonds) and non-polar solvents dissolve non-polar solutes. So for example, water is a polar molecule, so it will dissolve polar and ionicly bonded substanced. Non-polar solvents will dissolve non-polar covalently bonded substances.