# Osmotic Pressure &amp; Mass Percent

• kuahji
In summary, the conversation discusses the calculation of mass percents of KCl, KNO3, and Ba(NO3)2 in a solid mixture based on osmotic pressure and molar concentration. The initial steps involve converting units and using the osmotic pressure equation, but further calculations are needed to determine the moles of ions in the solution.
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?

kuahji said:
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?

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

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.

## 1. What is osmotic pressure?

Osmotic pressure is the pressure required to prevent the flow of water across a semi-permeable membrane, in order to maintain equilibrium between solutions of different concentrations.

## 2. How is osmotic pressure measured?

Osmotic pressure is measured in units of pressure, such as atmospheres (atm) or kilopascals (kPa), using an osmometer or other specialized equipment.

## 3. What is mass percent?

Mass percent is a way to express the concentration of a solute in a solution, calculated by dividing the mass of the solute by the total mass of the solution and multiplying by 100%.

## 4. How is mass percent related to osmotic pressure?

Osmotic pressure is directly proportional to the concentration of solute particles in a solution, so as the mass percent of a solute increases, so does the osmotic pressure.

## 5. What factors affect osmotic pressure?

The main factors that affect osmotic pressure include the concentration of solute particles, temperature, and the properties of the membrane used in the experiment.

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