Chapter 11: Problem 60
The osmotic pressure of a solution containing \(7.0 \mathrm{g}\) of insulin per liter is 23 torr at \(25^{\circ} \mathrm{C}\). Assuming ideal solution behavior, what is the molar mass of insulin?
Short Answer
Expert verified
The molar mass of insulin is approximately 5733 g/mol.
Step by step solution
01
Understand the Osmotic Pressure Equation
The osmotic pressure (\( \text{π} \) can be calculated using the formula: \( \text{π} = \frac{n}{V}RT \) where: \(n\) is the number of moles of solute, \(V\) is the volume of solution in liters, \(R\) is the ideal gas constant (0.08206 L·atm/mol·K), and \(T\) is the temperature in Kelvin. The pressure should be in units of atm.
02
Convert Pressure to Atmospheres
Convert the given osmotic pressure from torr to atmospheres: \( 1 \text{ atm} = 760 \text{ torr} \), so \( \text{π} = \frac{23 \text{ torr}}{760 \text{ torr/atm}} = 0.03026 \text{ atm} \).
03
Convert Temperature to Kelvin
Convert the given temperature from Celsius to Kelvin: \( T = 25°C + 273.15 = 298.15 \text{ K} \).
04
Rearrange the Osmotic Pressure Equation
Rearrange the equation to solve for the number of moles (\(n\)): \( n = \frac{\text{π}V}{RT} \).
05
Calculate the Number of Moles
Since \(V\) is 1 liter, the equation simplifies to: \( n = \frac{0.03026 \text{ atm}}{(0.08206 \text{ L·atm/mol·K}) (298.15 \text{ K})} \), compute to find the value of \(n\).
06
Compute the Molar Mass
Molar mass (\(M\)) is given by: \( M = \frac{\text{mass of solute (g)}}{\text{number of moles (mol)}} \), use the computed moles and the given mass to find the molar mass of insulin.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Molar Mass Determination
Molar mass determination is a critical aspect of chemistry that allows for the quantitative analysis of substances. It's defined as the mass of one mole of a given substance, generally expressed in grams per mole (g/mol). When it comes to osmotic pressure calculations, determining the molar mass of a solute, such as insulin, is vital.
By rearranging the osmotic pressure equation, you can find the number of moles of the solute in the solution. Once you have the number of moles and the mass of the solute used, the molar mass can be calculated simply by dividing the mass by the number of moles. This process involves a set of conversions and algebraic rearrangement to isolate the desired variable.
By rearranging the osmotic pressure equation, you can find the number of moles of the solute in the solution. Once you have the number of moles and the mass of the solute used, the molar mass can be calculated simply by dividing the mass by the number of moles. This process involves a set of conversions and algebraic rearrangement to isolate the desired variable.
Colligative Properties
Colligative properties, including osmotic pressure, boiling point elevation, freezing point depression, and vapor pressure lowering, are characteristics of solutions that depend on the ratio of the number of solute particles to the number of solvent molecules in a solution, and not on the nature of the chemical species present.
Osmotic pressure is a particularly important colligative property, especially in biological and chemical processes, as it describes the pressure required to prevent the inward flow of a solvent across a semipermeable membrane. Understanding these properties helps explain various phenomena, from preserving food to administering medication.
Osmotic pressure is a particularly important colligative property, especially in biological and chemical processes, as it describes the pressure required to prevent the inward flow of a solvent across a semipermeable membrane. Understanding these properties helps explain various phenomena, from preserving food to administering medication.
Solutions Chemistry
Solutions chemistry focuses on the study of homogeneous mixtures, where one substance is dissolved in another. The substance being dissolved is known as the solute, while the substance that dissolves it is the solvent.
Solutions are integral to various chemical processes and calculations, particularly when determining the properties of a solution based on its concentration. When calculating osmotic pressure, the concentration of the solution directly influences the resultant value, making precise concentration measurements a cornerstone of accurate solutions chemistry.
Solutions are integral to various chemical processes and calculations, particularly when determining the properties of a solution based on its concentration. When calculating osmotic pressure, the concentration of the solution directly influences the resultant value, making precise concentration measurements a cornerstone of accurate solutions chemistry.
Ideal Gas Law
The ideal gas law is a cornerstone of physical chemistry and provides a clear mathematical relationship between pressure, volume, temperature, and the number of moles of a gas. It's presented as PV=nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.
Although osmotic pressure calculations involve solutions and not gases, the ideal gas law is applied because osmotic pressure is analogous to the pressure exerted by a gas. This approach assumes ideal behavior in the solution, allowing the use of the gas constant in osmotic pressure equations. Hence, encapsulating the solute-solvent interactions in a manner similar to gas particles within a container.
Although osmotic pressure calculations involve solutions and not gases, the ideal gas law is applied because osmotic pressure is analogous to the pressure exerted by a gas. This approach assumes ideal behavior in the solution, allowing the use of the gas constant in osmotic pressure equations. Hence, encapsulating the solute-solvent interactions in a manner similar to gas particles within a container.