An aqueous solution containing 21.6 mg of Vasopressin in 100 mL solution produces Osmotic Pressure of 3.70 mmHg at 25°C. Calculate the Molecular Mass of Vasopressin.
Here's what I started working on, but then I got stuck.
21.6 mg = 0.0216 g
v = 100 mL = 0.1 L
ð = 3.70 mmHg = 0.004 atm
T = 25°C + 273.15 K = 298.15 K
ð = MRT
M = RT/ð
M = [(0.0821 L-atm/mol-K)(298.15 K)]/0.004 atm
I kept getting a weird answer for moles. ~ 6.12E10^3
M = (??? moles)/L (0.1 L)
M = ???
MM = (0.0216 g/ ???) =
But if I were to use 6.12E10^3, I wouldn't get the molar mass of Vasopressin, which I calulated using the Chemical Formula in order to double-check myself. Can you please help me out? It would be greatly appreciated! :)
Sure! I can help you with this problem. It seems like you're on the right track, but you made a mistake in your calculation.
To calculate the molecular mass of Vasopressin, you can use the ideal gas law equation, which is:
PV = nRT
Where:
P is the osmotic pressure in atm
V is the volume in liters
n is the number of moles
R is the ideal gas constant (0.0821 L-atm/mol-K)
T is the temperature in Kelvin
In this case, we know the osmotic pressure (P), volume (V), and temperature (T), and we want to solve for the number of moles (n). Rearranging the equation, we have:
n = PV / RT
Now let's substitute the given values into the equation:
P = 0.004 atm
V = 0.1 L
R = 0.0821 L-atm/mol-K
T = 298.15 K
n = (0.004 atm * 0.1 L) / (0.0821 L-atm/mol-K * 298.15 K)
When you plug in these values and calculate, you should get:
n ≈ 0.001622 moles
Now that you have the number of moles, you can calculate the molecular mass (MM) using the formula:
MM = mass / moles
Given that the mass is 0.0216 g and the number of moles is 0.001622, you can plug these values into the equation:
MM = 0.0216 g / 0.001622 mol
Calculating this should give you the molecular mass of Vasopressin.
I hope this helps! Let me know if you have any further questions.