How can you use chemical formulas to determine if a change is chemical or physical?

Draw metallic bonding if two copper

650.j is the same amount of energy as? 2720cal1550cal650.cal2.72cal

Some liquids can be distilled, but only at temperatures that are so high that it is impractical, or so high the compound decomposes. explain why distillation such compounds at significantly less than atmospheric pressure (some degree of vacuum) would solve this problem.