# Osmotic Pressure &amp; Mass Percent

1. Feb 3, 2008

### kuahji

[SOLVED] Osmotic Pressure &amp; Mass Percent

A solid mixture of KCL, KNO3, and Ba(NO3)2 is 20.92 mass percent chlorine, and a 1.000g sample of the mixture in 500.0 mL of aqueous solution at 25 C has an osmotic pressure of 744.7 mm Hg. What are the mass percents of KCl, KNO3, and Ba(NO3)2 in the mixture?

First I started out using osmotic pressure equation after I converted 744.7 mm Hg to atm.

.9799atm=7x(.08206 L*atm*K$$^{-1}$$*mol$$^{-1}$$)(298K)

x=.0057 mol of ions/liter (I chose 7x because it appears there would be 7 ions, assuming they'd all dissociate completely)

Here however is where I'm stuck already. Any advice on where to go from here?

2. Feb 4, 2008

### chemisttree

From here determine how many moles of ions are in half a liter.

3. Feb 6, 2008

### kuahji

I was able to figure it out from here, though it wasn't pretty. I ended up having to make two equations with two different variables. Thanks.