What is the osmotic pressure formed by dissolving 44.2 mg of aspirin (C9H8O4) in 0.358 L of water at 25 °C?

Name: Chemistry: The Central Science
Author: Brown
ISBN: 9780134414232

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Step 1: Convert the mass of aspirin from milligrams to grams by dividing by 1000. This will make it easier to work with in subsequent calculations.

Step 2: Calculate the number of moles of aspirin using its molar mass. The molar mass of aspirin (C9H8O4) can be found by adding the atomic masses of all the atoms in the formula.

Step 3: Determine the molarity of the aspirin solution by dividing the number of moles of aspirin by the volume of the solution in liters.

Step 4: Use the formula for osmotic pressure, \( \Pi = iMRT \), where \( i \) is the van't Hoff factor (which is 1 for non-electrolytes like aspirin), \( M \) is the molarity, \( R \) is the ideal gas constant (0.0821 L·atm/mol·K), and \( T \) is the temperature in Kelvin. Convert the temperature from Celsius to Kelvin by adding 273.15.

Step 5: Substitute the values for \( i \), \( M \), \( R \), and \( T \) into the osmotic pressure formula to find the osmotic pressure.

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Osmotic Pressure

Osmotic pressure is the pressure required to prevent the flow of solvent into a solution through a semipermeable membrane. It is directly proportional to the concentration of solute particles in the solution and can be calculated using the formula π = iCRT, where π is the osmotic pressure, i is the van 't Hoff factor, C is the molarity of the solution, R is the ideal gas constant, and T is the temperature in Kelvin.

Molarity

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. It is expressed in moles per liter (mol/L). To calculate molarity, one must first convert the mass of the solute (in this case, aspirin) into moles using its molar mass, and then divide by the volume of the solution in liters.

Van 't Hoff Factor

The van 't Hoff factor (i) indicates the number of particles into which a solute dissociates in solution. For non-electrolytes like aspirin, which does not dissociate into ions, the van 't Hoff factor is 1. This factor is crucial for accurately calculating colligative properties, including osmotic pressure, as it affects the total concentration of solute particles in the solution.