[sciencelogic]

Is it compulsory to change the calcium chloride of the drying tube of the previous reaction, whenever I want to do a new reflux? if not, how can i figure it out that when it's the correct time?

Thanks.

[AWK]

It depends - if you want to have a fairly anhydrous atmosphere of the reaction space, always use tubes with fresh, well-dried calcium chloride. If you want to have a dummy drying tube, use it repeatedly without changing the filling.

[sciencelogic]

It depends - if you want to have a fairly anhydrous atmosphere of the reaction space, always use tubes with fresh, well-dried calcium chloride. If you want to have a dummy drying tube, use it repeatedly without changing the filling.

Thanks
what temperature do you recommend for drying calcium chloride? And is there any formula to calculate the necessary MgSO4 for getting rid of the water contamination in a solution?

Thank you

[AWK]

Check phase diagram CaCl₂-H₂O or Wikipedia