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If I had a kettle which had limescale on it (due to several episodes of boiling hard water), and I would use it to boil distilled water, would that mean that some of the precipate dissolve into the distilled water, making that water harder than originally? If so, by how much?

I understand CaCO3 has very low solubility in normal conditions and requires CO2 to dissolve in higher amounts, but I'm not sure about how much is "low".

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    $\begingroup$ Yes, boiling distilled water in such a kettle would eventually dissolve any calcium carbonate deposit. Wikipedia lists the solubility as 0.013 g/L @25 C. $\endgroup$ – MaxW Aug 22 '18 at 19:19
  • $\begingroup$ This still seems like a fairly low number? That would be only 5mg Ca. My tap water has around 130mg/L Ca. What about magnesium? $\endgroup$ – Can Gencer Aug 22 '18 at 20:34
  • $\begingroup$ ...same result. Magnesium carbonate would eventually dissolve too. $\endgroup$ – MaxW Aug 22 '18 at 20:43
  • $\begingroup$ If it precipitated out of solution, it can go back in to solution (barring a chemical reaction that makes it insoluble). $\endgroup$ – Jon Custer Aug 22 '18 at 21:56
  • $\begingroup$ But if solubility of Ca is only 13mg/L, how come my tap water has 130mgCa/L ? $\endgroup$ – Can Gencer Aug 23 '18 at 12:28

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