Posted by yvonne on Saturday, November 29, 2008 at 10:21pm.
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  GK, Sunday, November 30, 2008 at 12:28am
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  GK, Sunday, November 30, 2008 at 12:29am
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 % )
Answer This Question
Related Questions
 chemistry  A sample of solid KCl (potassium chloride) weighing 0.500 g is mixed...
 AP Chem  A sample of solid KCl (potassium chloride) weighing 0.500 g is mixed ...
 chemistry  a mixture of NaCl and sucrose that has a combined mass of 10.20g is ...
 Gen Chem  A mixture of NaCl and sucrose (C12H22O11) of combined mass 10.2 g is ...
 Chemistry  A 10.00 gram solid sample consisting of a mixture of sodium chloride...
 biochem  You have the following stock solutions and solid chemicals in your lab...
 chem biochem bio  You have the following stock solutions and solid chemicals in...
 CHEMISTRY  At what temperature do KCL and KNO3 have the same solubility If a ...
 Chemistry Help? Thanks  At what temperature do KCL and KNO3 have the same ...
 Chemistry  7.5 g of a solid are added to 87.6g of water at 23.7 degrees C. When...
More Related Questions