which solution has highest freezing point if all are at the same molality
calcium chloride
sodium nitrate
potassium sulfate
iron(III) nitrate
all have same freezing point
please explain
look at the formulas:
CaCl2 ...three particles
NaNO3....two particles
K2SO4...three
Fe(NO3)3...four
Fe(NO3)3 will have the lowest freezing point (greatest freezing point depression), and sodum nitrate has the least depression, so it will have the highest fp.
To determine which solution has the highest freezing point, we need to understand the concept of colligative properties, specifically the freezing-point depression.
The freezing-point depression is a colligative property that depends on the number of solute particles dissolved in a solvent, rather than the identity of the solute. The more solute particles present in a solution, the greater the freezing-point depression.
In this case, we are given that all the solutions have the same molality, which means the same number of moles of solute per kilogram of solvent. Therefore, the number of solute particles will be the determining factor for the freezing-point depression.
Let's examine each solute and determine the number of solute particles they produce when dissolved in water:
1. Calcium chloride (CaCl2):
Calcium chloride dissociates into three ions when dissolved in water: one calcium ion (Ca2+) and two chloride ions (2Cl-). Therefore, it produces three solute particles.
2. Sodium nitrate (NaNO3):
Sodium nitrate dissociates into two ions when dissolved in water: one sodium ion (Na+) and one nitrate ion (NO3-). Therefore, it produces two solute particles.
3. Potassium sulfate (K2SO4):
Potassium sulfate dissociates into three ions when dissolved in water: two potassium ions (2K+) and one sulfate ion (SO42-). Therefore, it produces three solute particles.
4. Iron(III) nitrate (Fe(NO3)3):
Iron(III) nitrate dissociates into four ions when dissolved in water: one iron(III) ion (Fe3+) and three nitrate ions (3NO3-). Therefore, it produces four solute particles.
Since the freezing-point depression is directly proportional to the number of solute particles, the solution with the highest freezing point will be the one that produces the lowest number of solute particles. Therefore, sodium nitrate, which produces two solute particles, will have the highest freezing point among the given solutions.
The freezing point of a solution depends on the concentration of solute particles in the solvent. The greater the concentration of solute particles, the lower the freezing point of the solution.
To determine which solution has the highest freezing point, we need to compare the number of solute particles each compound dissociates into when dissolved in water.
1. Calcium chloride (CaCl2):
When dissolved in water, calcium chloride dissociates into three ions: one calcium ion (Ca2+) and two chloride ions (Cl-). So, one formula unit of calcium chloride produces three solute particles.
2. Sodium nitrate (NaNO3):
Sodium nitrate dissociates into two ions: one sodium ion (Na+) and one nitrate ion (NO3-). Hence, one formula unit of sodium nitrate produces two solute particles.
3. Potassium sulfate (K2SO4):
Potassium sulfate dissociates into three ions: two potassium ions (2K+) and one sulfate ion (SO42-). Thus, one formula unit of potassium sulfate produces three solute particles.
4. Iron(III) nitrate (Fe(NO3)3):
Iron(III) nitrate dissociates into four ions: one iron ion (Fe3+) and three nitrate ions (3NO3-). Therefore, one formula unit of iron(III) nitrate produces four solute particles.
Considering all the options, iron(III) nitrate produces the highest number of solute particles (four) when dissolved in water. Consequently, it has the greatest concentration of solute particles and thus the lowest freezing point.