**Find the molar mass of solute using osmotic pressure equations :**

**(B) A 25.00 mL aqueous solution containing 0.420 g of hemoglobin has an osmotic pressure of 4.6 torr at 27 degree celcius .What is molar mass of hemoglobin?**

**Strategy:**We have mass,volume,temperature and osmotic pressure.We can modify Π = MRT equation and use it to calculate molar mass

AS, M = m/MM where M = molarity ,

m= mass in grams

MM = molar mass

and as Π = MRT so Π = m RT/V(MM)

rearrangment given an equation for molar mass:

**MM = mRT/ ΠV** ------------> this is our desired equation for molar mass calculation

**Step 1 : Collecting all necessary datas required for the equation:**

m_{solute} = 0.420 g , R=0.082 L atm/mol K ,T = 27 c + 273 = 300 K, Π = 4.6 torr

**Step 2: Convert osmotic pressure given in torr to atm and volume to liters**

Π = 4.6 torr (1 atm/760 torr) = 6.05 x 10^-3 atm

V_{solution} = 25.00 mL(1l/1000 mL) = 2.5 x 10^-2 L

**Step 3: Switch all the datas in the desired equation to find the molar mass:**

MM = mRT/ΠV = 0.420g * 8.206 x 10-2 L atm/molK* 300 K / 6.05 x 10^-3 atm*2.500 x 10^-2 L

__MM = 6.8 x 10^4 g/mol__