The osmotic pressure (π) of a solution is given by the formula:
π=VnRT,
where n is the number of moles of solute, V is the volume of the solution, R is the ideal gas constant, and T is the temperature in Kelvin.
In this case, we are given that the osmotic pressure (π) is 3.0×10−43.0×10−4 atm, the volume (V) is 4.0 liters, and the temperature (T) is 27°C = 300 K.
We need to find the number of moles (n) of the polymer. Given that the mass of the polymer is 4 g, we can use its molar mass (M) to calculate n using the formula:
n=molar massmass.
Substituting the values:
n=M4g.
Now, we can substitute the values of n, V, R, and T into the osmotic pressure formula and solve for M:
π=VnRT.
3.0×10−4 atm=4 g4.0 L××300 K3.0×10−4atm=4.0LM4g×R×300K.
Solving for M:
3.0×10−4atm×4.0L×R×300K4g.
Given that R is the ideal gas constant, which is approximately 0.08206 L atm/mol K0.08206L atm/mol K, we can substitute its value:
M=4 g3.0×10−4 atm×4.0 L×0.08206 L atm/mol K×300 KM=3.0×10−4atm×4.0L×0.08206L atm/mol K×300K4g.
Solving for M:
M=82000 g/molM=82000g/mol.
Hence, the molar mass of the polymer is approximately 82000 g/mol, which matches the given answer.
The correct option is(B): 82000
Solutions are homogeneous mixtures of two or more substances, where the solute is uniformly dispersed in the solvent. Solutions can be classified into several types based on their composition and properties.
Understanding the different types of solutions is important for understanding their properties, behavior, and applications in various fields, such as chemistry, biology, and engineering.