Lysine is an amino acid that is an essential part of nutrition but which is not synthesized by the human body.What is the molar mass of lysine if 750.0 mL of a solution containing 8.60 g of lysine has an osmotic pressure of 1.918 atm?
T = 25.0°C
A)110.g/mol
B)146 g/mol
C)220.g/mol
D)1340 g/mol
E)1780 g/mol

Question

Quizplus · Accepted Answer

First, we need to find the number of moles of lysine in the solution:

n = mass/molar mass
n = 8.60 g/molar mass

Next, we need to convert the volume of the solution to liters and use the formula for osmotic pressure:

π = MRT
M = π/RT

where π is the osmotic pressure in atm, R is the gas constant (0.08206 L•atm/(mol•K)), and T is the temperature in Kelvin.

Converting the temperature to Kelvin:

T = 25.0°C + 273.15
T = 298.15 K

Converting the volume of the solution to liters:

750.0 mL = 0.750 L

Substituting the given values into the formula for M:

M = π/RT
M = 1.918 atm/(0.08206 L•atm/(mol•K)•298.15 K)
M = 0.0814 mol/L

Finally, we can solve for the molar mass of lysine:

n = M•V
8.60 g/molar mass = 0.0814 mol/L•0.750 L
molar mass = 147.8 g/mol ≈ 146 g/mol

Therefore, the best choice is B) 146 g/mol.

Lysine Is an Amino Acid That Is an Essential Part