Electrical conductivity of SiCl4

[Janiceleong26]

Why doesn't SiCl4 conduct electricity when it's in its molten state and conducts electricity when water is added? The answer is C. I know very well what is X and Z, but unsure what is Y.. Why not Al2O3? What's the difference? Does it got to do with their structures? Al2O3 is ionic with a degree of covalent character whereas SiCl4 is a simple molecular? if so, what is the effect of it?

 

[RUber]

According to: https://en.wikipedia.org/wiki/Aluminium_oxide
Aluminum oxide is insoluble in water, so adding water would probably not affect its conductivity.
You are right to look for the ionic bond.

 

[Borek]

What happens to each of those compounds when they are put into water? (Hint: "dissolve" and "doesn't dissolve" are not the only possible answers).

 

[Janiceleong26]

According to: https://en.wikipedia.org/wiki/Aluminium_oxide
Aluminum oxide is insoluble in water, so adding water would probably not affect its conductivity.
You are right to look for the ionic bond.

Thank you for the info. But SiCl4 is a simple molecular..it can react with water to form SiO2, but SiO2 is giant molecular! I'm really confused

 

[Janiceleong26]

What happens to each of those compounds when they are put into water? (Hint: "dissolve" and "doesn't dissolve" are not the only possible answers).

NaF will split and form Na+ and F-1 ions, SiCl4 reacts with water to form SiO2, and SiO2 has no reaction with water

 

[Bystander]

SiCl4 reacts with water to form SiO2

... and what else?

 

[Didian]

SiCl4 is not ionic, therefore it does not have free electrons to conduct electricity when in molten state.
However, when SiCl4 reacts with water, it form SiO2 and HCl. SiO2 is insoluble in water, but HCl conducts electricity since it's ionic.

Source from my school notes :D