Which is more effective at raising the boiling point of a soup? Why? SrBr2 Ca3N2 KCl CH4

##"Calcium nitride"##, mind you I would not want to eat the soup afterwards.

Boiling point elevation is proportional to the number of species in solution; it is a colligative property.

##KCl(s) rarr K^+ + Cl^-##

##SrBr_2(s) rarr Sr^(2+) + 2Br^(-)(aq)##

##Ca_3N_2(s) + 6H_2O rarr 3Ca^(2+) + 6HO^(-) + 2NH_3(aq) ##

Calcium nitride would give by far the most particles in solution on a per mole basis, and of course, the ammonia would speciate.

The only such contaminant I would put in my soup would be ##"sodium chloride"##. How would this affect the boiling point?

Methane. ##CH_4##, is a volatile, non-ionic species. You could use this to cook the soup.