[artem.metelskiy]

The concentration of iodine in sea wather is 60. parts per billion by mass. If one assumes that the iodine exists in the form of iodide anions. (the density of sea water is 1.025 g/mL.)
a) what is the molarity of iodide in sea water?
   
b)What is the molality of iodide in sea water?

Please help me how to get started on this problem, i have no idea.

[sjb]

The concentration of iodine in sea wather is 60. parts per billion by mass. If one assumes that the iodine exists in the form of iodide anions. (the density of sea water is 1.025 g/mL.)
a) what is the molarity of iodide in sea water?
   
b)What is the molality of iodide in sea water?

Please help me how to get started on this problem, i have no idea.

First, What is your definition of billion, and molarity / molality?

[artem.metelskiy]

I know formulas for Molarity and Molality
Molarity=amount (mol) of solute/volume (L) of solution
Molality=amount (mol) of solute/mass (kg) of solven

But I'm not sure about billion part

[sjb]

Hmm, therein lies my problem too, as the word billion is used to describe two different numbers. Are you aware of this too? If so, perhaps use one definition, explaining that's what you're doing and see if you can solve the problem that way.

[AWK]

http://en.wikipedia.org/wiki/Ppb