Can a solutions concentration change with a temp drop?

Question

If a chemical has a 6.38 % solubility at 20 Celsius and a 2.8 % at 0 Celsius does that mean that if the the temp of the solution drops from 20 to 0 then the solubility changes from 6.38 to 2.8 as well or since it is already dissolved will it keeps its original concentration?

Answer 1

they expand in heat and contract in cold.

Answer 2

The solubility at 0 C will be less than at 20 C. There will be less solute dissolved per unit volume at 0 C. If a solution has a solubility limit of 6.38 g/100 g at 20 C, and only 2.8 g/100 g at 0 C, then 3.58 g of solute will precipitate out (6.38 - 2.8) if the solution is cooled from 20 C to 0 C.

Answer 3

the solubility increases with temperature.  In other words, you can dissolve more stuff at higher temperature.

If you make a 2.8% solution at 20 C, and cool it down to 0 C, it will still be a 2.8 % solution.

But if you make a 6.38% solution at 20 C, and cool it down to 0 C, the resulting solution will be a 2.8% solution. The remaining stuff (solid) will precipitate out of the solution.