Why is calcium chloride (rock salt, CaCl2) more effective than sodium chloride (table salt, NaCl) at de-icing roads in the winter? A. Calcium chloride only breaks into 2 ions, while sodium chloride does not break up and remains 1 ion. B. Calcium is a larger molecule than sodium, so it has a greater effect. C. The additional chlorine atom forms a stronger bond between the atoms in calcium chloride than in sodium chloride, so calcium chloride remains one molecule while sodium chloride breaks apart. D. Calcium chloride breaks into 3 ions, while sodium chloride only breaks into 2 ions.

The correct option is;

D. Calcium chloride breaks into 3 ions, while sodium chloride only breaks into 2 ions

Explanation:

To help melt the ice on icy streets, calcium chloride (CaCl₂) is a more preferred salt type to sodium chloride (NaCl) as when it dissociates into ions in the ice, it forms three ions: a calcium ion, Ca²⁺, and two chloride ions, 2 Cl⁻, while sodium chloride forms two ions: one sodium ion, Na⁺, and one chloride ion, Cl⁻

According to the freezing point depression equation, we have;

ΔT = × m × i

Where;

ΔT = Change in freezing point temperature

= The freezing point depression constant

m = The solution's molality

i = van't Hoff factor

The calcium chloride salt will cause the most depression because the van't Hoff factor is 3 for calcium chloride and 2 for sodium chloride.

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.