# Ion concentration

1. Nov 5, 2007

### temaire

[SOLVED] Ion concentration

1. The problem statement, all variables and given/known data
http://img225.imageshack.us/img225/9918/chemch0.jpg [Broken]​

2. Relevant equations
C = n/v

3. The attempt at a solution
My work is shown up above. Sorry if my work looks a little messy. My answer is 27.6 grams.

Last edited by a moderator: May 3, 2017
2. Nov 5, 2007

### temaire

I just want someone to tell me if I'am right, and correct me if I'am not.

3. Nov 5, 2007

### eli64

good effort

MgBr2 --> Mg+2(aq) + 2Br-(aq)

the bromide ion is twice the concentration of the MgBr2 so the moles of MgBr2 is half what you calculated (.15/2).

4. Nov 6, 2007

### temaire

But isn't Br supposed to have a subscript of 2?

5. Nov 6, 2007

### eli64

MgBr2 is a compound that dissociates into its ions in water.

the Br- ions don't stay together in water so you get 2 Br- ions

Br2 by itself is only written when you are referring to bromine as an diatomic element, not as ions in solution

6. Nov 6, 2007

### temaire

Thanks a lot for the help.