Talk:Urea

:I'm not sure were you take your data from. But if you are talking on solubility of Urea in H2O, then one has to look on the German Wiki page. Taking there the reference, ie. CRC-Handbook of Chemistry and Physics, one finds on page "5-166" a value for the max. solubility of 54.4% mass fraction, ie. one can put 1200 g Urea in 1000 g H2O at 25 °C (almost your value of 1188 g per liter).

:I'm not sure were you take your data from. But if you are talking on solubility of Urea in H2O, then one has to look on the German Wiki page. Taking there the reference, ie. CRC-Handbook of Chemistry and Physics, one finds on page "5-166" a value for the max. solubility of 54.4% mass fraction, ie. one can put 1200 g Urea in 1000 g H2O at 25 °C (almost your value of 1188 g per liter).

:However, when talking on concentration in Molarity i.e. moles per liter of solution one has to take into account the volume increas by the solution process. When using the table on page "5-133" from the CRC-Handbook (which is valid for 20 °C) one can plot the molar concentration values against mass fraction and fit a second order polynomial and find a max. concentration of ~ 10.5 mol/L @ 55%. The value of almost 20 mol / kg is the maximum Molality (i.e. moles of solute per kg of water), also atainable from the values given in the CRC-Handbook and fitted with a third order polynomial up to 55% mass fraction. [[User:Wolfkil|Wolfkil]] ([[User talk:Wolfkil|talk]]) 17:08, 18 February 2026 (UTC)

:However, when talking on concentration in Molarity i.e. moles per liter of solution one has to take into account the volume increas by the solution process. When using the table on page "5-133" from the CRC-Handbook (which is valid for 20 °C) one can plot the molar concentration values against mass fraction and fit a second order polynomial and find a max. concentration of ~ 10.5 mol/L @ 55%. The value of almost 20 mol / kg is the maximum Molality (i.e. moles of solute per kg of water), also atainable from the values given in the CRC-Handbook and fitted with a third order polynomial up to 55% mass fraction. [[User:Wolfkil|Wolfkil]] ([[User talk:Wolfkil|talk]]) 17:08, 18 February 2026 (UTC)

::Works out to 1196.46g/L at that temp from a water weight of 997.05g/L at {{val|25|u=C}} which is close enough to the g/kg value that it doesn't really matter unless someone needs a saturated solution at that specific temperature, and only then because the dissolution is so endothermic that you'd need to add urea to very hot water (or apply heat) to get that much into solution so it would be possible for 1200g to dissolve and then 3.54g to precipitate out when it returns to 25C. That may rarely matter to someone, I dunno. I'm not sure how hot the water would need to be initially since dissolving just ~400g in {{cvt|1|USgal}} of {{cvt|125|F}} water lowers the temperature well below room temp. I imagine getting a saturated solution would require letting it sit stirring for quite a long time. [[User:A Shortfall Of Gravitas|A Shortfall Of Gravitas]] ([[User talk:A Shortfall Of Gravitas|talk]]) 02:43, 20 April 2026 (UTC)