How Many Ions are Present in 1 Formula Unit of HI, HBr, and N2S5?

[name_ask17]

Homework Statement

How many ions are present in 1 formula unit of HI(aq)?
HBr(g)?
N2S5?

Homework Equations

These two questions have the same concept, I believe.
I went the simple way and thought the answer was 2 for both of them, but apparently that was wrong. Can someone show me how to do this, please?

The Attempt at a Solution

Does it have something to do with these compounds being consisted of diatomic molecules?
HI(aq) is 2, but HBr(g) is not 2. I'm guessing it has something to do with the fact that one is aq and the other is a gas, but how does that affect it? How many ions would HBr(g) have?
And the N2S5 one is not 7 ions. Why? I am confused. Please help!

 

[Borek]

HI(aq) - where do the ions come from?

 

[name_ask17]

H+ and I- so the answer to that one is 2 ions, right?
But what I'm confused on is HBr(g). Why wouldn't that also be 2 ions?

 

[Borek]

What is the process that creates H⁺ and I^- in HI(aq)?

 

[name_ask17]

dissociation in aq solution.
but how does that help me see the HBr? its a gas so it's not dissociating right?

 

[Borek]

but how does that help me see the HBr? its a gas so it's not dissociating right?

Yes.

Can't help you with the N₂S₅. As far as I know such compound doesn't exist.

 

[name_ask17]

so i still don't understand HBr would have only 1 ion then? or none?

 

[Borek]

None, it doesn't dissociate, so there are only molecules present.

 

[name_ask17]

ohhh i understand. thank you
so i know you said that you didnt know about the n2s5.. but since it also doesn't dissociate, it it also 0 ions? does that make sense or no?
or would it be 2 ions for the n2 and s8? i don't really know, actually.

 

[Borek]

If you HAVE to give some answer other than "question doesn't make sense", then 0 makes the most sense.

 

[name_ask17]

does it have something to do with it being a binary molecular compound?

 

[Borek]

Sorry, no idea what you are asking about. What does have something to do with N₂S₅ being a binary molecular compound?

(actually - in the context of the question - it doesn't matter if it is a binary compound or not, it doesn't exist and the story ends there)

 

[name_ask17]

ok i will talk to my professor about it. thank you so much for your help. i appreciate it.