Hemoglobin is the oxygen-carrying protein found in red blood cells. To determine the molar mass of hemoglobin, 29.0 mg of the protein is dissolved in water at 4°C to make 2.0 mL of solution. Hemoglobin does not dissociate in water. The osmotic pressure of the solution was found to be 3.57 torr.
A. What is the molarity of the solution?
B. How many moles of hemoglobin are dissolved in the solution?
C. What is the molar mass of hemoglobin?
I don't get why it's giving me the temperature and osmotic pressure. Am I supposed to do something with this? And how do I calculate the molar mass of hemoglobin from this as opposed to just using the molecular formula and a periodic table? Thanks.
A. What is the molarity of the solution?
B. How many moles of hemoglobin are dissolved in the solution?
C. What is the molar mass of hemoglobin?
I don't get why it's giving me the temperature and osmotic pressure. Am I supposed to do something with this? And how do I calculate the molar mass of hemoglobin from this as opposed to just using the molecular formula and a periodic table? Thanks.
-
Although you could certainly find the molecular formula, the problem doesn't give you the molecular formula of hemoglobin. You are supposed to use the formula
osmotic pressure = MRT where M is the molarity, R is the gas law constant .08206 L atm per mol per kelvin, and T is the Kelvin temperature.
a) (3.57/760) atm = M (.08206 L atm per mol per kelvin)(277 K) and you solve for molarity
b) then multiply the molarity by .0020 liters to get the number of moles
c) then .029 grams divided by the number of moles is the molar mass
osmotic pressure = MRT where M is the molarity, R is the gas law constant .08206 L atm per mol per kelvin, and T is the Kelvin temperature.
a) (3.57/760) atm = M (.08206 L atm per mol per kelvin)(277 K) and you solve for molarity
b) then multiply the molarity by .0020 liters to get the number of moles
c) then .029 grams divided by the number of moles is the molar mass