A physical change is required, usually a change in state like evaporation or condensation.For example, when separating salt from saltwater, you need to evaporate the water so it turns into gas, leaving the salt behind. Walang chemical reaction na nangyayari — binabago lang ang anyo (state) ng isa sa mga components.In short: You need to apply a physical change (like heating or cooling) to separate the parts of a solution.