What Is the White Layer on Water?

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Discussion Overview

The discussion revolves around the phenomenon of a white layer that forms on the surface of water when it is boiled, as experienced by a customer. Participants explore the nature of this layer, its composition, and potential solutions to the issue, touching on aspects of water quality and mineral content.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant describes a customer's issue with a white oily layer appearing on boiled water and questions whether it is actually oil or something else.
  • Another participant suggests that the white layer may be due to calcium or "hardness" in the water.
  • A follow-up question is raised regarding why the white layer only appears when the water is heated, indicating a lack of understanding about the underlying chemistry.
  • A later reply proposes a chemical reaction involving calcium bicarbonate converting to calcium carbonate when heated, which could explain the formation of limescale.
  • It is noted that while the presence of calcium may enhance the taste of water, it could also lead to practical issues such as increased soap usage and the need for kettle maintenance.

Areas of Agreement / Disagreement

Participants express differing views on the composition of the white layer, with some proposing it is calcium-related while others consider the possibility of it being oil. The discussion remains unresolved regarding the exact nature of the layer and the best solution.

Contextual Notes

There are unresolved questions about the specific conditions under which the white layer forms and the implications of water hardness on household appliances.

Who May Find This Useful

Individuals interested in water quality, chemistry of minerals in water, or practical issues related to household water use may find this discussion relevant.

mathsTKK
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I met a customer who face a problem in the water quality in the house. The water supply is clean and clear but when it is boiled or cooked, a white oily layer floats on top of the water. When the water is left cooled, the white layer hardens and sticks on the wall of the pot and container. The customer claims that a sand filter has been used to filter the water but the white layer still appear. Currently, I predict that's actually a layer of oil and I can use a paper layer filter to remove the oil. However, I wonder whether that's really oil layer or something else. Can someone tell me what's actually the white layer in the water? and what's the solution to the problem?

Thank you very much^^
 
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Thank you russ_watters^^ But can I ask why the white layer only appear when the water is heated? I still don't understand why this situation occurs...

Anyway, thank you once again and I hope for more replies soon^^
 
In solution it's Calcium bicarbonate, when you heat it the reaction forms calcium carbonate (limescale)
Ca(HCO3)2(aq) → CO2(g) + H2O(l) + CaCO3(s)

It means your water tastes nice and will have lots of useful minerals in it - at the cost of using a bit more soap and needing a new kettle every few years.
 

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