# Chemistry

posted by .

hellppp please i have a test on this on mondayy im so screwed
A solid mixture contains MgCl2 and NaCl. When 0.5000 g of this solid is dissolved in enough water to form 1.000 L of solution, the osmotic pressure at 25°C is observed to be 0.4010 atm. What is the mass percent of MgCl2 in the solid? (Assume ideal behavior for the solution.)

• Chemistry -

Osmotic pressure is given by:
π = MRT
π = osmotic pressure in atm
Mi = moles of particles/liter <- unknown
R = 0.0821 L.atm/K.mol
T = 298 K

• Substitute and solve for Mi to moles of ions per liter.
• Divide M by 3 to get the overall molarity, M, in terms of MgCl2 formula units.
• Multiply M by the molar mass of MgCl2 to get grams / liter which is equal to grams/(1000mLs)
• Divide by 10 to get grams / 100 mLs = ___%

(NOTE: We assume the density of the solution is close to 1.00 g/mL, so that grams/100mLs is about the same as the mass % )

• Chemistry -

Osmotic pressure is given by:
π = MRT
π = osmotic pressure in atm
Mi = moles of particles/liter <- unknown
R = 0.0821 L.atm/K.mol
T = 298 K

• Substitute and solve for Mi to moles of ions per liter.
• Divide Mi by 3 to get the overall molarity, M, in terms of MgCl2 formula units/L.
• Multiply M by the molar mass of MgCl2 to get grams / liter which is equal to grams/(1000mLs)
• Divide by 10 to get grams / 100 mLs = ___%

(NOTE: We assume the density of the solution is close to 1.00 g/mL, so that grams/100mLs is about the same as the mass % )

## Similar Questions

1. ### Chemistry

7.5 g of a solid are added to 87.6g of water at 23.7 degrees C. When the solid has all been dissolved and thoroughly mixed with the water, the temperature of the solution is decreased by 6.2 degrees C. Calculate the heat of the solution …
2. ### AP Chem

A sample of solid KCl (potassium chloride) weighing 0.500 g is mixed with an unweighed sample of solid MgCl2 (magnesium chloride) and the mixture is then completely dissolved in water to form a clear solution. An aqueous solution of …
3. ### chemistry

A sample of solid KCl (potassium chloride) weighing 0.500 g is mixed with an unweighed sample of solid MgCl2 (magnesium chloride) and the mixture is then completely dissolved in water to form a clear solution. An aqueous solution of …
4. ### Chemistry Help? Thanks

At what temperature do KCL and KNO3 have the same solubility If a saturated solution of KNO3 at 20.0 C is heated to 80.0 how much more could be dissolved?
5. ### CHEMISTRY

At what temperature do KCL and KNO3 have the same solubility If a saturated solution of KNO3 at 20.0 C is heated to 80.0 how much more could be dissolved?
6. ### biochem

You have the following stock solutions and solid chemicals in your lab: 1.5M NaCL 0.2M Tris buffer, pH 8.0 10 mg/ml Bovine serum albumin (BSA) MgCl2 (solid, anhydrous) MW = 95.211 g/mole (95% pure) How would you make 250 ml of the …
7. ### chem biochem bio

You have the following stock solutions and solid chemicals in your lab: 1.5M NaCL 0.2M Tris buffer, pH 8.0 10 mg/ml Bovine serum albumin (BSA) MgCl2 (solid, anhydrous) MW = 95.211 g/mole (95% pure) How would you make 250 ml of the …
8. ### Chemistry

A 10.00 gram solid sample consisting of a mixture of sodium chloride and potassium sulfate is dissolved in 100.0 mL of water is combined with another 200.0 mL solution that contains excess aqueous lead(II) nitrate. Upon mixing the …
9. ### chemistry

a mixture of NaCl and sucrose that has a combined mass of 10.20g is dissolved in enough water to make up to a 250mL solution. osmotic presdure of solution is 7.32atm at 23℃. calculate the mass percent of NaCl
10. ### Gen Chem

A mixture of NaCl and sucrose (C12H22O11) of combined mass 10.2 g is dissolved in enough water to make up a 250 mL solution. The osmotic pressure of the solution is 8.29 atm at 23°C. Calculate the mass percent of NaCl in the mixture.

More Similar Questions