Mixing Solutions: Understanding Volume & Enthalpy

Click For Summary

Discussion Overview

The discussion centers on the behavior of solutions, specifically addressing why there may be no change in volume and enthalpy when two components are mixed. It explores concepts related to ideal solutions, Raoult's law, and molecular interactions in the context of mixing liquids.

Discussion Character

  • Conceptual clarification
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that an ideal solution is defined as one where the change in volume and enthalpy upon mixing is zero.
  • Others argue that Raoult's law applies to ideal solutions and is observed when components are of the same nature.
  • A participant notes that mixing two volumes of the same liquid results in no change in total volume or heat effects due to unchanged molecular interactions.
  • It is suggested that when mixing similar liquids, the volume and enthalpy changes will be minimal because the energetic interactions are comparable to those in the original pure liquids.

Areas of Agreement / Disagreement

Participants express varying definitions and understandings of ideal solutions, with some agreement on the characteristics of ideal solutions but no consensus on the implications for volume and enthalpy changes during mixing.

Contextual Notes

Limitations in the discussion include assumptions about molecular interactions and the specific conditions under which Raoult's law applies, which are not fully explored.

kartikwat
Messages
49
Reaction score
0
Why there no change in volume and enthalpy of solution when two components are mixed
 
Chemistry news on Phys.org
What is the definition of an ideal solution?
 
Solution which follows raoutlts law over all range of concenteration.
 
And its components are of same nature
 
An ideal solution is one for which the change in volume and enthalpy upon mixing are zero. Raoults law follows indirectly from this. Many combinations of real species exhibit behavior close to ideal solution behavior.

Chet
 
Chestermiller said:
An ideal solution is one for which the change in volume and enthalpy upon mixing are zero. Raoults law follows indirectly from this. Many combinations of real species exhibit behavior close to ideal solution behavior.

Chet

So my question is why enthalpy or volume doesn't change
 
If you mix two volumes of the same liquid, the total volume doesn't change, and there are no heat effects because the molecular interactions don't change. If you mix two liquids whose molecules are very similar, the volume and enthalpy will change very little, because the energetic interactions between the molecules of the solution will be very similar to those of the original pure liquids. For more details on this, see Smith and Van Ness, intro to chem engg thermo.

Chet
 

Similar threads

Calculating heat released from excess enthalpy
  • · Replies 1 ·
Replies
1
Views
2K
High Temp γ-Fe Enthalpy > Low Temp α-Fe Enthalpy: Why?
  • · Replies 1 ·
Replies
1
Views
1K
Why are more polarized bonds weaker (Acid dissociation)?
  • · Replies 0 ·
Replies
0
Views
2K
What is the difference between internal energy and enthalpy?
  • · Replies 12 ·
Replies
12
Views
3K
Can Calorimeters Measure Enthalpy Variation of Fast Reactions?
  • · Replies 3 ·
Replies
3
Views
2K
Enthelpy vs Internal Energy in Phase Change
  • · Replies 12 ·
Replies
12
Views
5K
Thermodynamics: Why does salt lower the melting point of ice?
  • · Replies 21 ·
Replies
21
Views
8K
How is enthelpy different than heat?
  • · Replies 2 ·
Replies
2
Views
3K
Excess Enthelpy for Water-Ethanol Solution
  • · Replies 1 ·
Replies
1
Views
4K
Need Help understanding energy and enthelpy please
  • · Replies 6 ·
Replies
6
Views
2K