Solubility of several substances

[chemist2b]

are these soluble in water?

Na2Cr2O7 (i think yes)

(NH4)2Cr2O7 (i think yes)

PbCr2O7 (i think no)

CuI2 (no? whay is this disproving by rule that iodides and chlorides are soluble in water except for heavy metals?)

 

[chemisttree]

Maybe copper is a heavy metal?

 

[Borek]

CuI2 (no? whay is this disproving by rule that iodides and chlorides are soluble in water except for heavy metals?)

There is no such compound, so it is hard to say if it is soluble.

This is a very specific case.

 

[chemist2b]

so this was the equation i was given: KI + CuSO4---> something

i assumed it was k2S04 and CuI2

this is supposed to be either no reaction or double repleacement

maybe having the whole equatoin helps?

but the other three were correct, right?

 

[Borek]

this is supposed to be either no reaction or double repleacement

Actually it is neither. And it is really not that difficult to check, some googling should help you quite fast.

but the other three were correct, right?

Yes.

 

[chemist2b]

so if i cancel out spectators, it is a synthesis reaction (most sites agree that cuI2 is insoluble in water)

Cu +2 (aq) + 2I -1(aq) ---> CuI2 (s)

what i don't understand is why it is disproving my solubility rule (iodides are insoluble except for heavy metals, and copper isn't a heavy metal).

ps. you can be awful at googling. if i was good at it i would probably not have to ask these questions here.
:(

 

[Borek]

Show me one site that lists CuI₂ as insoluble.

 

[chemist2b]

hte site of the sheet that my teacher gave me. it says "ss" for slightly soluble which he told us to assume meant insoluble. but i gues the chart isn't that reliable. because llokibng now at the other ones i see mostly blanks but one or two say soluble. thanks...

 

[Borek]

hte site of the sheet that my teacher gave me. it says "ss" for slightly soluble which he told us to assume meant insoluble. but i gues the chart isn't that reliable. because llokibng now at the other ones i see mostly blanks but one or two say soluble. thanks...

Are you sure it shows solubility of copper(II) iodide and not solubility of copper(I) iodide?

In water solutions in the presence of iodides copper(II) oxidizes iodides to iodine and gets reduced to copper(I), this is followed by copper(I) iodide precipitation. CuI is weakly soluble, CuI₂ doesn't exist.