which of the following liquids have the highest freezing point?
a- aqueous Fe(NO3)3 (0.030)
b- aqueous glucose (0.050 m)
c- aqueous NaI (0.030 m)
d- aqueous NaI (0.010 m)
e- pure water
please explain the concept behind it as well thank you!
so water would have the highest freezing point?
it wouldn't be aqueous NaI at 0.010 m ? i thought that lower concentration means higher freezing point, or is that only if they are all the same compound ?
The freezing point of a liquid is related to its concentration. Generally, the higher the concentration of solute particles in a liquid, the lower its freezing point. This is due to the fact that the solute particles disrupt the regular arrangement of the solvent particles, making it more difficult for them to form a solid lattice structure.
In this case, we can determine the liquid with the highest freezing point by comparing the concentrations of the solutes.
a- aqueous Fe(NO3)3 (0.030): This solution has a concentration of 0.030 mol/L of Fe(NO3)3.
b- aqueous glucose (0.050 m): This solution has a concentration of 0.050 mol/L of glucose.
c- aqueous NaI (0.030 m): This solution has a concentration of 0.030 mol/L of NaI.
d- aqueous NaI (0.010 m): This solution has a concentration of 0.010 mol/L of NaI.
e- pure water: Pure water does not have any solute particles, so it has a higher freezing point compared to any of the solutions listed above.
Based on the given concentrations, the aqueous glucose (b) would have the highest freezing point among the listed options. This is because it has the highest solute concentration of 0.050 mol/L, indicating a higher freezing point compared to the other options.
To determine which of the given liquids has the highest freezing point, we need to understand the concept of colligative properties. Colligative properties depend on the number of particles present in a solution, rather than the specific type of particles.
The freezing point depression is one such colligative property. When a solute (such as a salt or sugar) is added to a solvent (such as water), the presence of the solute particles disrupts the regular arrangement of the solvent particles, making it more difficult for the solvent to freeze.
In this case, all the options involve aqueous solutions or pure water. The freezing point depression of an aqueous solution depends on the concentration of solute particles.
Comparing the given options:
a- aqueous Fe(NO3)3 (0.030): This solution contains Fe(NO3)3, which dissociates into four particles (one Fe³⁺ ion and three NO₃⁻ ions). Thus, the concentration of solute particles is 0.030 mol/L × 4 = 0.120 mol/L.
b- aqueous glucose (0.050 m): Glucose does not dissociate into ions, so the concentration of solute particles is equal to the molarity given, which is 0.050 mol/L.
c- aqueous NaI (0.030 m): NaI dissociates into two particles (one Na⁺ ion and one I⁻ ion). So, the concentration of solute particles is 0.030 mol/L × 2 = 0.060 mol/L.
d- aqueous NaI (0.010 m): Similar to option c, NaI dissociates into two particles. The concentration of solute particles is 0.010 mol/L × 2 = 0.020 mol/L.
e- pure water: Pure water has no solute particles, so the concentration is 0.
Now, the freezing point depression is directly proportional to the concentration of solute particles. A higher concentration of solute particles leads to a larger freezing point depression.
Comparing the concentrations, the highest concentration is in option a, aqueous Fe(NO3)3 (0.030 mol/L), which corresponds to the highest freezing point depression. Therefore, option a has the highest freezing point among the given liquids.
delta T = i*Kf*m
You want the one that has the smallest delta T since that will give you the highest freezing point/
All you need to do is to evaluate i*Kf*m
Kf is a constant so you can ignore that.
Evaluate i*m for each. But if you do all of that you're wasting your time.
Pure water freezes at 0 C. Right? All of the solutions freeze lower than 0 C. Right? So which is the highest freezing point?