Explanation on Colligative Properties

[Ibraiz]

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Colligative properties are properties of solutions that depend on the number of molecules in a given volume of solvent and not on the properties (e.g. size or mass) of the molecules.[1] Colligative properties include: lowering of vapor pressure; elevation of boiling point; depression of freezing point and osmotic pressure.

The underline above properties like boiling point is not just dependent on the amount of molecules present but also on physical properties as h-bonding. Then how is this a colligative property?

What are all the colligative properties we need to memorize or know for DAT?

Thank you

 

[Erhatstil]

Colligative properties are properties of solutions that depend on the number of molecules in a given volume of solvent and not on the properties (e.g. size or mass) of the molecules.[1] Colligative properties include: lowering of vapor pressure; elevation of boiling point; depression of freezing point and osmotic pressure.

The underline above properties like boiling point is not just dependent on the amount of molecules present but also on physical properties as h-bonding. Then how is this a colligative property?

What are all the colligative properties we need to memorize or know for DAT?

Thank you

boiling point is not effected exclusively by hydrogen bonds or by molecules in solution. both of these factors can affect the boiling point.

for the dat, knowing what the colligative properties, as you underlined should be enough.

 

[winnie bear]

Colligative properties are properties of solutions that depend on the number of molecules in a given volume of solvent and not on the properties (e.g. size or mass) of the molecules.[1] Colligative properties include: lowering of vapor pressure; elevation of boiling point; depression of freezing point and osmotic pressure.

The underline above properties like boiling point is not just dependent on the amount of molecules present but also on physical properties as h-bonding. Then how is this a colligative property?

What are all the colligative properties we need to memorize or know for DAT?

Thank you

I think the main idea behind colligative properties is to compare an impure solution with a pure solvent. In the case of BP elevation, since the vapor pressure for a solution is less than that of the solvent, and BP is when Pv=Patm, by the time a pure solvent boils, the solution hasn't reached boiling point yet since the solution has to overcome the impurities getting in the way plus the atmospheric pressure, whereas the pure solvent only has to overcome external pressure.

Hope this helps!