What is the osmotic pressure of a solution prepared by dissolving 5.50 g of CaCl2 in enough water to make 420. mL of solution at 29.2°C?
pi = osmotic pressure = i*M*RT
i = van't Hoff factor which for CaCl2 is 3
M = molarity = mols/L. You know moles from 5.5/molar mass CaCl2 and volume is 0.420 L = ?
R = gas constant. Use 0.08206 and pi will be in atmospheres.
T = kelvin temperature.
Post your work if you get stuck.
Hi thank you so much I was using the wrong van't Hoff factor before.
To determine the osmotic pressure of a solution, we can use the following equation:
π = i * M * R * T
Where:
- π is the osmotic pressure
- i is the van't Hoff factor (the number of particles the solute dissociates into)
- M is the molarity of the solution
- R is the ideal gas constant (0.0821 L*atm/mol*K)
- T is the temperature in Kelvin
First, let's calculate the molarity (M) of the solution:
1. Convert the mass of CaCl2 from grams to moles:
molar mass of CaCl2 = 40.08 g/mol (Ca) + 2 * 35.45 g/mol (Cl)
moles of CaCl2 = 5.50 g / (40.08 g/mol + 2 * 35.45 g/mol)
2. Determine the volume of the solution in liters:
volume of solution = 420 mL = 420 mL / 1000 mL/L
3. Calculate the molarity of the solution:
Molarity (M) = moles of CaCl2 / volume of solution
Now, let's calculate the osmotic pressure using the equation provided. The van't Hoff factor (i) for CaCl2 is 3 since it dissociates into three ions (1 Ca²⁺ ion and 2 Cl⁻ ions) in water.
4. Convert the temperature to Kelvin:
T(K) = 29.2°C + 273.15
5. Plug the values into the equation:
π = i * M * R * T
Calculate the osmotic pressure using the given values.
Finally, provide the answer to the question, stating the osmotic pressure of the solution.
To determine the osmotic pressure of the solution, we can use the formula:
osmotic pressure (π) = (n/V)RT
Where:
n is the number of moles of solute
V is the volume of the solution in liters
R is the ideal gas constant (0.0821 L·atm/(mol·K))
T is the temperature in Kelvin
First, let's calculate the number of moles of CaCl2:
molar mass of CaCl2 = (40.08 g/mol) + 2*(35.45 g/mol) = 110.98 g/mol
moles of CaCl2 = (mass of CaCl2) / (molar mass of CaCl2)
= 5.50 g / 110.98 g/mol
Next, let's convert the volume to liters:
volume of the solution = 420 mL = 420/1000 L
Now, we need to convert the temperature to Kelvin:
temperature in Kelvin = 29.2°C + 273.15
Finally, we can substitute the values into the formula to calculate the osmotic pressure:
osmotic pressure (π) = (n/V)RT
= (moles of CaCl2 / volume of solution) * (0.0821 L·atm/(mol·K)) * (temperature in Kelvin)
Just plug in the respective values into the formula and calculate to find the osmotic pressure of the solution.