Which of the following solutions would have the highest osmotic pressure?
0.15 M KCl
0.2 M C6H12O6
0.2 M C12H22O11
0.2 M CH3COOH
0.15 M CaCl2
pi = i*M*RT.
i = van't Hoff factor.
i = 2 for KCl
i = 1 for C6H12O6
i = 1 for C12H22O11
i = 1 for CH3COOH
i = 3 for CaCl2
Note that you don't need to actually calculate pi to do this; i.e., R and T are constants; all you need are i and M. i*M is the determining factor.
To determine which solution would have the highest osmotic pressure, we need to calculate the osmotic pressure for each solution. Osmotic pressure is directly proportional to the molar concentration of a solute.
The formula to calculate osmotic pressure (π) is given by:
π = MRT
Where:
- π is the osmotic pressure
- M is the molar concentration of the solute
- R is the ideal gas constant (0.0821 L·atm/(mol·K))
- T is the temperature in Kelvin (K).
Let's calculate the osmotic pressures for each solution:
1. For 0.15 M KCl:
π = (0.15 mol/L) * (0.0821 L·atm/(mol·K)) * (T in K)
2. For 0.2 M C6H12O6:
π = (0.2 mol/L) * (0.0821 L·atm/(mol·K)) * (T in K)
3. For 0.2 M C12H22O11:
π = (0.2 mol/L) * (0.0821 L·atm/(mol·K)) * (T in K)
4. For 0.2 M CH3COOH:
π = (0.2 mol/L) * (0.0821 L·atm/(mol·K)) * (T in K)
5. For 0.15 M CaCl2:
π = (0.15 mol/L) * (0.0821 L·atm/(mol·K)) * (T in K)
The molar concentration is the same for options 2, 3, and 4, so their osmotic pressures will be equal if the temperature is the same. The osmotic pressures depend on the temperature, but we cannot determine the highest osmotic pressure without knowing the specific temperature.
Therefore, we cannot determine which of the solutions would have the highest osmotic pressure without additional information about the temperature.
To determine which solution would have the highest osmotic pressure, we need to consider the number of particles the solute dissociates into when it dissolves in water. The more particles present, the higher the osmotic pressure will be.
Let's analyze each solution:
1. 0.15 M KCl: KCl dissociates into two ions (K+ and Cl-), so it will have a total of 2 particles.
2. 0.2 M C6H12O6: C6H12O6 (glucose) does not dissociate into ions when it dissolves, so it will remain as a single particle.
3. 0.2 M C12H22O11: C12H22O11 (sucrose) also does not dissociate into ions and will remain as a single particle.
4. 0.2 M CH3COOH: CH3COOH (acetic acid) partially dissociates into an acetate ion (CH3COO-) and a hydrogen ion (H+), so it will have more than one particle.
5. 0.15 M CaCl2: CaCl2 dissociates into three ions (Ca2+ and two Cl-), resulting in a total of 3 particles.
Based on the analysis, the solution with the highest osmotic pressure would be 0.15 M CaCl2, as it will have the highest number of particles.
Therefore, the correct answer is 0.15 M CaCl2.