A compound is known to be a cesium halide, CsX. If 3.00 grams of the salt is dissolved in exactly 100.0 grams of water, the solution freezes at -0.735°C. What is the chemical formula for the salt?

Question

i know it would be

-0.735= -1.86 * m

m= 3g/ X g/mol/kg solvent

however the answer I get from that doesn't work, please help

Answer 1

Your mistake is you didn't take into account the van't Hoff factor, i.
The equation is delta T = i*Kf*m
is for CsX is 2.