Understanding Enthalpy: How Salting Crushed Ice Cools Beer Faster

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Discussion Overview

The discussion revolves around the phenomenon of salting crushed ice to cool beer more effectively, with a focus on understanding the underlying principles through the concepts of enthalpy and entropy.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • One participant suggests that salting ice allows it to liquify at a temperature below freezing, which eliminates insulating air spaces and enhances heat exchange with the beer.
  • Another participant expresses a need to understand the cooling effect in terms of enthalpy and entropy, indicating a desire for a deeper explanation involving molecular interactions and energy transfer.
  • A participant mentions the enthalpy of melting ice and the enthalpy of crystallization of salt as relevant factors, prompting consideration of how entropy changes during these processes.
  • There is a reference to ion-dipole bonds weakening due to increased entropy, which is suggested as a reason for energy being absorbed from the beer, leading to cooling.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of using enthalpy and entropy to explain the cooling effect, with some focusing on practical heat exchange principles while others seek a more theoretical understanding. The discussion remains unresolved regarding the complete role of enthalpy and entropy in this context.

Contextual Notes

Participants have not fully defined the assumptions related to enthalpy and entropy, and there are unresolved questions about the specific calculations or values mentioned, such as the enthalpy for the reactants.

Who May Find This Useful

This discussion may be useful for students studying thermodynamics, particularly those interested in practical applications of enthalpy and entropy in cooling processes.

Saska
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Can someone help me understand this:

By salting the crushed ice, the beer got cold faster.

Why?! I have recently studied some Enthalpy, so if anyone could give me an explanation to this using anything related to Enthalpy I'd be very grateful!
 
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You don't even need enthalpy IMO.

In general, an object immersed in liquid water will exchange heat with the liquid faster than it will with ice cubes - because of insulating air spaces.

Salt allows the ice to liquify at a "below freezing" temperature, getting rid of the insulating air spaces. Colligative property of NaCl -> lowering freezing point of water.
 
For school I need to know and understand this using enthalpy and enthropy. :)

Thanks for the answer. Let me go through it, look up some words in a dictionary and I'll be right back!

EDIT: OK I read through your reponse. It makes sense but isn't there much more to it? For exampleI have no idea where enthropy and enthalpy comes into the picture.

My friend (who is, unfortunately, offline now and won't be able to help anymore) talked about bonds between the atoms and molekyles.

He said something about the increasing enthropy which causes the ion-dipole bonds to weaken, and that's why energy is taken from the beer, which then gets cold.

He also, some way got the enthalpy for the reactants (2648 kj/mol) ...
 
Last edited:
You should look both at the enthalpy of melting of ice and the enthalpy of crystallization of salt. Likewise, you should think about what is entropy and how does it change when ice melts. How does it change when both ice melts and salt dissolves?
 

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