[fardeen_gen]

Decrease in freezing point of solvent is observed due to presence of solute. This decrease depends only on no. of particles of solute present in the solution. When 30 g of acetic acid is dissolved in 1kg of C6H6(benzene), the expected decrease in freezing point is approximately 2.5°C, but the actual decrease is only around 1.2°C. Comment on the observation.(The question is from Chemical Bonding chapter)

[enahs]

What happens to acetic acid when you put it in water?

[Dan]

Read about colligative properties. If you examine the formula for freezing point deperession you should notice that the "expected" value given is probably based on the assumption that the Van 't Hoff factor is equal to 1. The lower than expected experimental result is down to the Van 't Hoff factor being less than 1 - this is what you have to explain.

[fardeen_gen]

Thanks for the replies. I know that the answer is relatef to Vant' Hoff factor. But I need to answer this question keeping only chemical bonding in mind. Is the answer something to do with hydrogen bond?

[Borek]

Thanks for the replies. I know that the answer is relatef to Vant' Hoff factor. But I need to answer this question keeping only chemical bonding in mind. Is the answer something to do with hydrogen bond?

Hydrogen bond plays a role here. However, nobody asks you to explaing things using ONLY Van't Hoff factor. Van't Hoff factor gives here very important hint about what is happening in the solution; once you will know what is happening, you will see how hydrogen bond fits.

You may also try the other way - if you have some idea about what may be happening in the solution, check if that will be consistent with observed freezing point decrease.

[fardeen_gen]

Thats what the problem is. I don't know at all what happens in the solution.

[Borek]

Thats what the problem is. I don't know at all what happens in the solution.

What does Van't Hoff factor tell you about? What value does it have? When can it have this value?