How volatile impurity affects boiling point of a liquid?

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Discussion Overview

The discussion revolves around the effects of volatile and non-volatile impurities on the boiling point of a liquid. Participants explore theoretical concepts, definitions, and implications of these impurities in relation to boiling point changes, referencing Raoult's law and vapor pressure dynamics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant asserts that non-volatile impurities increase the boiling point of a liquid and questions whether volatile impurities decrease it.
  • Another participant suggests that more volatile substances tend to boil first and asks for definitions related to boiling point and the impact of non-volatile impurities on boiling point, hinting at Raoult's law.
  • A participant explains that impurities block molecules from transitioning to the gaseous state, leading to decreased vapor pressure and thus requiring more energy to reach boiling point.
  • There is a discussion about whether the presence of volatile impurities would result in higher vapor pressure due to their own tendency to vaporize.
  • One participant clarifies that it is not solely about energy but rather about achieving a higher temperature for the solvent's partial pressure to equal external pressure, suggesting the use of Raoult's law to demonstrate this.

Areas of Agreement / Disagreement

Participants express differing views on the effects of volatile impurities on boiling point, with some questioning their impact on vapor pressure while others provide explanations that suggest a complex relationship. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants reference Raoult's law and the concept of vapor pressure, but there are limitations in the clarity of definitions and assumptions regarding the behavior of volatile versus non-volatile impurities.

Brwahussen
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I know that non volatile impurities increases the boiling point of a liquid.

Does volatile impurity decreases the boiling point? How?
 
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In general more volatile things boil first, don't they?

What is the definition of the boiling point? Why does the presence of non-volatile impurity increase the BP temperature? (hint: Raoult's law). Can you extend this line of thinking?
 
Borek said:
In general more volatile things boil first, don't they?

What is the definition of the boiling point? Why does the presence of non-volatile impurity increase the BP temperature? (hint: Raoult's law). Can you extend this line of thinking?
Because the presence of impurities will block more molecules to jump to gaseous state so the vapore pressure will decrease, hence more energy is needed to elevate vapore pressure to environment pressure and higher boiling point is resulted.

So, does presense of volatile impurity will cause higher vapore pressure? Because it vaporizes it by itself

[sorry if my English is bad]
 
Brwahussen said:
Because the presence of impurities will block more molecules to jump to gaseous state so the vapore pressure will decrease

OK

hence more energy is needed to elevate vapore pressure to environment pressure and higher boiling point is resulted.

It is not exactly about energy (although in a way you are right, you need energy to heat up the mixture), more like you need a higher temperature so that the partial pressure of the solvent becomes equal to the external pressure. But in general you are on the right track. Note that is pretty easy to show using Raoult's law (try!).

So, does presense of volatile impurity will cause higher vapore pressure? Because it vaporizes it by itself

Yes.

[sorry if my English is bad]

Actually it is not just bad, it is atrocious :wink: But everyone has to start somewhere.
 
Borek said:
OK
It is not exactly about energy (although in a way you are right, you need energy to heat up the mixture), more like you need a higher temperature so that the partial pressure of the solvent becomes equal to the external pressure. But in general you are on the right track. Note that is pretty easy to show using Raoult's law (try!).
Yes.
Actually it is not just bad, it is atrocious :wink: But everyone has to start somewhere.
Thanks!
:)

And I will keep improving my english ;).
 
Brwahussen said:
And I will keep improving my english ;).

Popracuj popracuj, warto.
 

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