CaCl2, NaCl, and sugar derived from beet juice are all commonly used in winter to melt ice on streets. At the same molality, which of these would be most effective at this task and why?
delta T =i*K*molality
So look at this sensibly.
m is the same for all, K is the same for all, so delta T changes only with i, the van't Hoff factor and that is the number of particles per mole of the material.
CaCl2 has ? when dissolved in water.
NaCl has ?when dissolved in water
Suar (C12H22O11) has ? when dissolved in water.
Your answr is what?
CaCl2
To determine which compound would be most effective at melting ice on streets, we need to compare their colligative properties, specifically their freezing point depression ability. The compound with the greatest freezing point depression will be the most effective at melting ice.
The freezing point depression is determined by the molality of the solution using the formula:
∆Tf = Kf * m
Where:
∆Tf is the freezing point depression
Kf is the cryoscopic constant (a characteristic property of the solvent)
m is the molality of the solution
Since the molality is taken to be the same for all three compounds, we can compare the cryoscopic constants (Kf) for the solvents: water (in ice) and beet juice.
The cryoscopic constant (Kf) for water is approximately -1.86 °C/m.
The cryoscopic constant (Kf) for beet juice is not readily available, but assuming beet juice has a similar cryoscopic constant to water, we can compare the effectiveness of the compounds based on their concentrations.
CaCl2 and NaCl dissociate completely in water and form multiple ions, while sugar does not dissociate and remains a single molecule.
Since a higher concentration of solute particles in the solution would result in a greater freezing point depression, CaCl2 and NaCl would be more effective at melting ice compared to sugar (from beet juice), assuming equal molality.
Therefore, between CaCl2, NaCl, and sugar derived from beet juice, CaCl2 and NaCl would be more effective at melting ice on streets due to their ability to dissociate into multiple particles and produce a greater freezing point depression. However, it is important to note that the actual effectiveness may also depend on other factors such as cost, availability, and environmental impact.
To determine which substance would be most effective at melting ice on streets, we need to look at their properties and how they interact with water.
Molality is a measure of the concentration of a solute in a solvent and is defined as the number of moles of solute per kilogram of solvent. Since we are comparing substances at the same molality, we can assume an equal concentration for all three.
1. CaCl2 (Calcium chloride):
- When dissolved in water, it dissociates into calcium ions (Ca2+) and chloride ions (Cl-).
- Calcium chloride has a strong affinity for water and is hygroscopic, meaning it attracts moisture from the air.
- It is effective at lower temperatures compared to other de-icing agents and can work at temperatures below -20°C.
- Calcium chloride can also create an exothermic reaction with water, generating heat and accelerating the melting process.
2. NaCl (Sodium chloride):
- Common table salt, when dissolved in water, dissociates into sodium ions (Na+) and chloride ions (Cl-).
- Sodium chloride is relatively effective at melting ice and snow but has limitations at very low temperatures.
- It is less effective than calcium chloride at extremely cold temperatures below -10°C.
3. Sugar derived from beet juice:
- Beet juice-derived sugar does not dissociate into ions like calcium chloride or sodium chloride.
- The sugar present in beet juice can lower the freezing point of water, preventing ice formation at temperatures below 0°C.
- However, it is generally less effective compared to salt-based de-icers like calcium chloride and sodium chloride.
Considering these factors, the most effective substance at the same molality for melting ice on streets would be CaCl2 (Calcium chloride). It has a stronger ability to attract moisture, lower freezing point, and works at lower temperatures compared to NaCl (Sodium chloride) and sugar derived from beet juice.